I've heard a sermon where the priest interpreted this sentence in a way that this message of Jesus was not intended for Thomas, but it was intended for later generations (just like us, living today):

Before his death and resurrection Jesus already announced that he would no longer be "visible" on earth after Ascension day.

Later generations would dream of being in the situation of the Apostles and have an evidence that Jesus has really resurrected.

Jesus' sentence should comfort these people - including us, who are living today: According to that sentence it is not a disadvantage, but an advantage for us that we don't have any evidence...

For what it's worth, Jesus did not say "Cursed are you, Thomas, because you have not believed what you have not seen." It's not clear Jesus rebukes Thomas here. Instead, he encourages other disciples in their faith by calling them "blessed" or "privileged" or "superlatively happy."

John the Gospel-writer's first audience was, many believe, a beleaguered community of Jesus-followers stuck behind closed doors for their safety. Jesus's words in this verse encourage them, especially the skeptical among them, to see Jesus's resurrection and one another with eyes of faith. His same words acknowledge and encourage the skeptical among us.

John the Gospel-writer only quotes Jesus saying this form of the word "blessed" (μακάριοί) in one other place, in the account of the Last Supper at John 13:17 in his (foot-washing) example of how his followers might live lives of service. In that passage he refers to the disciple who will rat him out to the temple bigshots, and draws a clear distinction between the blessed ones and the not-blessed one.

When Jesus rebukes a disciple in the Gospels, he does it unambiguously ("get behind me, Satan" and catching Peter's eye as Peter denies him). These post-resurrection words, by contrast, are pastoral and encouraging. In the 21st century, the last thing we want to do is rebuke skeptics.

It's easy to see this as a lesson for Thomas, but Jesus regularly used the people and events around Him to teach valuable lessons. He certainly knew that the events He and His apostles were living in would be recorded.

So He might not have been speaking to Thomas — He might have been providing some really valuable insight into the people the Twelve would speak to later.

First: Stubbornness is one of the enemies of conviction

An old adage teaches "faith precedes the miracle." The concept is simple: no matter what we may think, it's actually rare for a miracle to lead to conversion. A person who doesn't want to change often won't, even in the face of obvious evidence or tremendous pressure. Many people who know addicts know this to be true.

There is a problem with the demand for better evidence when no such evidence is forthcoming. Thomas was blessed in that the evidence (unbeknownst to him) was forthcoming. Perhaps he could have expected it having heard of first-hand accounts from the others. We, the spiritual descendants of the Twelve, don't have that privilege.

So what happens when we do witness a miracle? As the scriptures teach, a few may blossom and thrive because of it, but most will fall among thorns, or rocks, etc. Said another way, if we're unwilling to prepare the soil of our faith to accept the seeds of the gospel, we're unlikely to gain real faith.

Conclusion #1: it's better to choose to believe than to wait for hard evidence because the effort expended to make that choice opens our hearts in ways hard evidence cannot.

Second: In a gospel founded on freedom to choose, compulsion will always be treated as second-class.

One of my favorite verses comes from the book of Revelation. "I know thy works, that thou art neither cold nor hot: I would thou wert cold or hot. So then because thou art lukewarm, and neither cold nor hot, I will spue thee out of my mouth."

Think about that! Jesus will respect people who make a conscious choice to reject Him over and above anyone who is wishy-washy, who won't use the glorious and precious gift of free choice. Please don't misunderstand me, there is no free ride for people who choose to sin — only that Jesus has little respect for people who refuse a gift from God. And the symbolism of that low regard? The forcible removal of said person from the body of Christ. (1 Cor 12.)

Another aspect of this comes from the parables of the talents and pounds: everyone freely chose to act and were rewarded for their choice — but the one who was afraid to act, who would have had to have been compelled to act, was punished (in one case, destroyed!).

Remember, I suspect the lesson was more an opportunity to prepare the Twelve for their upcoming missions, not a rebuke of Thomas. Thomas was simply being reminded that free choice is not a gift to be ignored.

Conclusion #2: The Lord respects people who respect Him, and the choice to believe is more respectable than the expectation of proof.

Third: You cannot serve two masters.

Finally, allow me to briefly use a phrase from my own church: "it is not meet that I should command in all things; for he that is compelled in all things, the same is a slothful and not a wise servant." This is reflected in one of the most famous of Biblical verses: "No servant can serve two masters: for either he will hate the one, and love the other; or else he will hold to the one, and despise the other."

It may seem mean-spirited to simply clump people who want better evidence with those who must be compelled, but in the end, there's little difference. A person who simply wants better evidence is one who chooses to believe and is convicted of that choice, yet continues to strive for the greater evidences God has for His children. In most cases, people looking for better or hard evidence are really looking for validation of their desire to not believe.

People who require hard evidence may (perhaps even often) be resentful that they were proven wrong. It may not be a strong feeling, but the Natural Man being what he is, it will gnaw at the back of a person's mind almost forever — always leading to a less-than-100% commitment.

Conclusion #3: the desire to have better evidence is too often a temptation to validate faith, meaning we have not chosen to serve one master. We've chosen to serve two.

Jesus honours those that believe God's (his) Word, irrespective of what they see.

Peter was an eye-witness of the glory of the Lord Jesus, seeing and hearing that Jesus is the Christ the Son of God, and yet says:

For we have not followed cunningly devised fables, when we made known unto you the power and coming of our Lord Jesus Christ, but were eyewitnesses of his majesty. For he received from God the Father honour and glory, when there came such a voice to him from the excellent glory, This is my beloved Son, in whom I am well pleased. And this voice which came from heaven we heard, when we were with him in the holy mount. We have also a more sure word of prophecy; whereunto ye do well that ye take heed, as unto a light that shineth in a dark place, until the day dawn, and the day star arise in your hearts: Knowing this first, that no prophecy of the scripture is of any private interpretation. For the prophecy came not in old time by the will of man: but holy men of God spake as they were moved by the Holy Ghost. (2Pe 1:16-21)

Jesus said he would rise again, and he did - instead of believing the Word of Jesus and the eyewitnesses, Thomas demands his own form of evidence...

The Scriptures foretold the death and resurrection of the Christ (1 Cor 15:3-4). Christ did not expect Thomas (or us) to believe it WITHOUT evidence - Prophecy of the Old Testament is evidence. The Prophecies, Works and Person of Christ is Evidence! The Apostles as reliable eyewitnesses is evidence!

So that leaves Thomas and us with three very strong pieces of evidence - the Prophetic Word of God, ensuring such a Person and Event; The Spirit, Word and works of Jesus, to confirm He is that Person; and reliable eye-witnesses of the fulfilment of the Prophetic Event.

Thomas still did not believe! Yet, the tender love of Christ is even demonstrated in his condescension to the arrogance of Thomas to doubt the Word of God, Christ himself and the eye-witness testimony of his brothers: He met him in his doubt. But not without the admonishment it deserves and pronounced blessing on those that will rest in the Word of God, through the Prophets, Christ and testimony of the Apostles. There is no leap of Faith to believe Him who cannot lie!

Why does Jesus value leap of faith more than those who rely on direct evidence?

I don't think you can get that from the text. One really big argument against that is that the text itself says that when Jesus appeared to the other disciples, he "showed them his hands and his side" (Jn 20:20). Thomas is only wanting to have the same experience that the others had already had. We should probably hear him intone "unless I also see..."

A question worth asking is "why is John telling us this?". A clue is the sudden and repeated appearance of the word 'believe' in ch 19 and 20, not least of all in the final sentence of the entire work, hard on the heels of the Thomas episode: "these are written so that you may believe that Jesus is the Christ, the Son of God, and that by believing you may have life in his name". This is probably what is in view when the 2nd disciple "saw and believed" in Jn 20:8 ... not simply that the resurrection happened but that it meant that Jesus is the Messiah as they had been hoping all along. Certainly Thomas does not say "so, I see now that the resurrection really did occur ... fascinating!" ... he declares Jesus to be "My Lord and my God!" (and Jesus calls this 'belief').

Yahweh says of the Messiah in in the covenant with David (2 Sam 7) that He will "establish the throne of his kingdom forever". Jesus can't both be dead and be the Messiah. It's not just that a dead Messiah is rather useless, but by definition he never could have been the Messiah if he's dead.

If anything, John ends with a concession to the difficulty of swallowing the unexpected and breathtaking event of the resurrection. He paints a portrait of how difficult it was for Thomas to believe before he saw, and (I think, gently) invites the reader to believe despite not having the opportunity to see. It's not that Jesus values this act of faith more, but for most of us, circumstances require it!

Jesus was validating Thomas' doubt

Jesus made a ridiculous claim: that he was going to rise bodily from the dead. I'm always amazed at modern Christians who gloss over that. Jesus could have easily made an unfalsifiable claim like he would "spiritually rise". Since there's no objective definition there, nobody could disprove that to his followers. By making an objective claim, Jesus was creating a scenario where there would be no ambiguity at all. Either he did or didn't rise from the dead. And if he hadn't arisen, nascent Christianity could have been destroyed by producing Jesus' body.

The number of Jesus' followers who actually believed this before it happened was... zero. No apostles, no followers... nobody. Believe it or not that was the point of this. Jesus knew they wouldn't believe and he wasn't just OK with it, it was part of the plan. Peter and John run to the empty tomb and leave bewildered. It's not until Jesus shows up in the flesh that anyone believes.

Jesus isn't rebuking Thomas. Jesus is commending Thomas for hanging out until he, too, gets the same proof the other apostles already had. This wasn't something minor Thomas was being asked to believe because virtually nobody comes back from the dead. You can argue that Lazarus should have been a clue, but you run into the problem of the 10 other apostles in the same boat. And that brings me to the point point Jesus was likely trying to make in the moment (and wisely making to all future Christians at the same time):

Thomas is not less of an Apostle for this. Thomas was asked to believe something exceptionally hard to accept on faith alone. But accept it he did, to the point that he would spend the rest of his life telling others about it, and never recanting.

Non-Christian here, so I don't represent the Christian view on the subject.

What is evidence? If you've seen an egg fall to the floor and break, is that enough evidence to "believe" in gravity? How about seeing a video of it happening? How about if I tell you that I've seen an egg fall and break? How about if I tell you that I've seen the video?

At some point, we have to consider the input of our senses to be evidence enough. Every person chooses for himself where that point is. Many people who believe in their religion, be them Christians, or Jews, or Muslims, or any of the tens of other religions we share, have received enough proof through their experiences to believe. Some have survived car crashes. Some have survived terrorist attacks. Some have survived war. Is this really direct evidence of a divine power? Every person decides this for himself. The experience of an egg falling and breaking could be faked by occurring inside an accelerating rocket. Yet, though my entire life may have been simulated inside an accelerating rocket, I consider my experiences with gravity to be convincing. To me.

The leap of faith is not in lieu of direct evidence. It is accepting the evidence that you have.

Sign vs. Spiritual Truth

Resurrection is merely an empirically verifiable SIGN to point to the spiritual truth: that Jesus is God, our Messiah, our Lord, our Judge, our Brother, our Priest, etc. There are numerous examples in both the OT and the NT where God gave someone a miracle to believe that a prophecy or a promise comes truly from God. Jesus's bodily resurrection is a SIGN that the Father gave us so that it is reasonable to believe NOT the resurrection itself (because resurrection was proven), but to entrust our lives to Jesus so one day we will be bodily resurrected like Jesus.

A good example is Gideon asking for a sign before agreeing to lead Israel to fight Midian. There is no indication that God was upset at Gideon. After being satisfied by the sign, Gideon STILL needed an act of faith that God is not going to abandon him mid-way in the battle! Similarly, I don't think Jesus was upset at Thomas's request. All of the apostles who verified with their hands and eyes of Jesus's resurrection still needed a lot of faith in their hard ministries which ended in martyrdom (except John).

Three referents of believe

Let's look at verses 27-29 (NIV) very closely:

²⁷ Then he said to Thomas, “Put your finger here; see my hands. Reach out your hand and put it into my side. Stop doubting and believe.” ²⁸ Thomas said to him, “My Lord and my God!” ²⁹ Then Jesus told him, “Because you have seen me, you have believed; blessed are those who have not seen and yet have believed.”

There are 3 different things that can be believed by the occurrences of the verb "believe":

1. That Jesus is indeed died and resurrected bodily
2. That Jesus is Lord and God
3. That someone's testimony of point #1 is true

Thomas didn't believe #3, then after touching Jesus he believed #1 as with the other disciples, and in verse 28 he also believed #2.

I propose that:

• Like Gideon, it is commendable to want direct evidence for #1 (the sign). We shouldn't fault Thomas (nor ourselves) for wanting #1; it's only fair he should be given opportunity for empirically verifying Jesus's bodily resurrection like the rest of the disciples eight days prior.

• It is also commendable to want good evidence for #3 (the trustworthy testimony), this is where historiography, Biblical research, etc. come in. We can use our unaided reason to assess #3, no leap of faith is needed at this point. There are many, many scholarly resources that back up the reliability of the Gospels as trustworthy by reason alone:

  • Craig Blomberg's 2007 book Historical Reliability of the Gospels, the 2nd edition of the 1987 1st edition which I read a long time ago.
  • C.S. Lewis famously arrived at the conclusion that the Gospel is True Myth by his reasoning alone. (See this 2018 Master's Thesis "C.S. Lewis and the True Myth: A Reconciliation of Theology, Philosophy, and Mythology" for detail).

• The referent of Jesus's "believe" in verse 27 is either #1 (the sign) or #3 (the testimony) but the referent of Jesus's "believe" in verse 29 is #2 (the spiritual truth). Thus, the "leap of faith" is to move from #1 to #2, not from #3 to #1. Christianity teaches that to profess that "Jesus is Lord" and "Jesus is God" requires God's grace.

• We are disadvantaged because in order to believe #1 we have to believe #3 first. But what Jesus wants us to have eventually is #2. It's no use to believe #1 if we are not going to believe #2.

Conclusion:

• Jesus's blessing is for anyone who believe #2 whether they are the select few who witness #1 firsthand, or for us who need to believe #3 as well. Jesus expects us to use all our intelligence to arrive at #1 (plus #3), and His Holy Spirit will aid us to arrive at #2 (the final destination).

• The whole Gospel of John can be seen as leading the reader on a journey with Jesus until the end (resurrection). The climax is thus at verse 20:28, where posed with evidence for #1, we too, like Thomas, can make the same confession that Jesus is Lord and God (#2).

• To profess #2 we need to believe that Jesus is who He claimed to be in Chapters 1 to 19, who is WAAAY more than an ethical teacher, but as the Jesus:

  • who existed before Abraham (John 8:58),
  • who is in the Father and the Father is in him (John 14:10),
  • who came into the world he created (John 1:10),
  • who can give life to anyone he wants and who received from the Father the authority to judge (John 5:21-22),
  • etc.

I think Charles R's answer and some others are on the right track. But you seem to be looking for something "more", so let me zoom out a bit. My contention is that Jesus's comment to Thomas is making a point about religion, generally, as humans experience it.

Religion and science are two different tools for pursuing knowledge. In science, we might say that a new paper we read looks pretty good, their experimental methodology seems sound, etc., but the real test comes when someone else tries to reproduce the results. If they can't, we conclude that the original authors screwed up somehow. If someone proposes a new model for something, it needs to make falsifiable predictions about things we don't yet know. If we measure those things and they match the model, we say it's useful; if not, we say that at best, that model doesn't always work, and we start looking for a better one.

Religions, at least the most popular ones, don't work like that. Miracles cannot be reliably reproduced on demand by just anyone (if they could, we'd call them technology, or at least magic, rather than miracles.) Divine intervention cannot be reliably predicted; God tells us what to do, not the other way around, and so it is in most faiths. So we need a different way of determining the truth, like comparing eyewitness reports against prophecy and/or doctrine to see if things jive or not.

(There are those who are so attached to one of these two ways of thinking that they reject the other as inherently invalid, but we definitely don't have time to get into that here.)

Thomas, as you pointed out, heard from the other disciples that Jesus was risen, but didn't believe it until he saw for himself - he wanted, you might say, to see if he could reproduce their results. In this case, the answer was yes, but I would argue that Jesus is pointing out that in what we call "matters of faith" (i.e. for questions pertaining to the supernatural), as a general heuristic, that's not really gonna work.

After all, if miracles have happened throughout history but you only believe in the ones that you've personally witnessed, you're going to be disbelieving the vast majority of true stories of miracles, which means you will be wrong about an awful lot of things. So when do you start believing and trusting? When all your friends, who've spent years following a dude around and really ought to know what he looks like, tell you they saw Him? When an angel shows up to bug you directly (Gideon)? When a burning bush starts talking to you (Moses)? When fire is literally raining from the sky (Pharaoh)? Each of them doubted to an extent that can be seen as comical - at some level, they didn't want to believe. But if you don't want to lose pretty much everything that matters to you (Pharaoh) or be chastised thousands of years later by talking vegetables saying "Me you believe, but from God you need a sign?!" (Gideon) or have your name enter the lexicon as an idiom for someone who never believes anything (Thomas), sooner or later you've gotta decide that whether you can see for yourself or not, the preponderance of the evidence suggests something is happening - and the rest is faith.

The issue with Thomas was that he already had evidence, but he wanted a specific kind of evidence in addition to that.

Jesus told them that He was leaving then coming back, even taking them to His Father’s house. Thomas had the evidence of God’s word.

For this reason the Father loves me, because I lay down my life that I may take it up again. - ‭‭John‬ ‭10:17‬ ‭ESV‬‬

Let not your hearts be troubled. Believe in God; believe also in me. In my Father’s house are many rooms. If it were not so, would I have told you that I go to prepare a place for you? And if I go and prepare a place for you, I will come again and will take you to myself, that where I am you may be also. - ‭‭John‬ ‭14:1-3‬ ‭ESV‬‬

A little while, and you will see me no longer; and again a little while, and you will see me. … So also you have sorrow now, but I will see you again, and your hearts will rejoice, and no one will take your joy from you. - ‭‭John‬ ‭16:16, 22‬ ‭ESV‬‬

From God’s lips, Thomas heard the promise. Notwithstanding, he needed evidence from human eyes. He received the evidence he sought and finally believed. But those who believe based on God’s word, without adding their own requirements, are more blessed.

Jesus Himself experienced the temptation to trust His eyes more than His ears.

And the tempter came and said to him, “If you are the Son of God, command these stones to become loaves of bread.” But he answered, “It is written, ‘Man shall not live by bread alone, but by every word that comes from the mouth of God.’” - ‭‭Matthew‬ ‭4:3-4‬ ‭ESV‬‬

In the wilderness, after nearly 6 weeks of fasting, Jesus faced an opportunity to doubt: “If you are the Son of God…” Looking around, what would He have seen? A wilderness instead of a palace fitting a king. Looking at Himself, He would have seen a carpenter’s son, emaciated from His fast. If He trusted His eyes, the tempter had reason to question if He was the son of God. So the tempter demanded proof.

But Jesus did not fall for it. He responded that we are to live “by every word that comes from the mouth of God.” Instead of trusting His eyes or seeking more proof of His being the Son of God, He trusted the prof already given by the word of God. What word?

This is my beloved Son, with whom I am well pleased. - ‭‭Matthew‬ ‭3:17‬ ‭ESV‬‬

Before He went into the wilderness of temptation the Father assured Him of His Sonship. Then comes the tempter to get Him to doubt what He heard, to make Him provide more proof. But Jesus essentially said, “No, God’s word is enough proof.”

Had Thomas had the same faith, he would have greeted news of Christ’s return not with doubt, but with joy that his expectation had come to pass. Jesus was saying that those who believe the word of God are more blessed than those who require the sight of man.

But let’s not think that Thomas was the only one who suffered from this malady.

Then the other disciple, who had reached the tomb first, also went in, and he saw and believed; for as yet they did not understand the Scripture, that he must rise from the dead. - ‭‭John‬ ‭20:8-9‬ ‭ESV‬‬

John “saw and believed.”

On the evening of that day, the first day of the week, the doors being locked where the disciples were for fear of the Jews, Jesus came and stood among them and said to them, “Peace be with you.” When he had said this, he showed them his hands and his side. Then the disciples were glad when they saw the Lord. - ‭‭John‬ ‭20:19-20‬ ‭ESV‬‬

They gathered behind locked doors because they were afraid. It wasn’t until they saw Him that they were glad.

So Thomas is not alone. Many have difficulty taking God at His word. Blessed are those who believe His word.

Jesus does not expect us to have faith with no evidence. He wants us to trust that His word is all the evidence we need.

You have to realize that Jesus himself had foretold his resurrection (John 2:19, Matthew 12:39-40). In addition to this, there was Scripture prophecy to the same effect (Ps. 16:10 cf. Acts 13:35, Luke 24:15-27). Testing a message against Scripture rather than simply accepting it blindly is something that is commended throughout the Bible (1 John 4:1, Acts 17:11, Deut. 13:1-3) but this is not what Thomas did. Instead, he had a skeptical attitude about the things that both Jesus and the prophets had foretold, even when it was confirmed to him by eye witnesses. As a skeptic, he eventually arrived at the truth; but he was the last to do so, and he almost missed it entirely! Jesus' rebuke is for Thomas' unreadiness to believe the promises of God. This is a call to search out and believe God's Word, not a call to gullibility.

(For further clarification, see Numbers 14. The Isrealites first refused to believe God's promise and go into the land. Afterward, they attempt to go in after He has told them not to. The first is a failure to believe God (doubt) and the second is a faith in something God has not promised (presumption). Both errors result in tragedy.)

The answer begins where the problem began; in the Book of Beginnings, in the Garden of Eden and in what has corrupted humanity.

The temptation was "When you eat of it your eyes will be opened and you shall be like God, knowing Good and Evil." - Genesis 3:5

Adam had proof because he was spoken to directly by God and was in the presence of God daily. He chose to contradict the testimony of God and he fell: His nature was changed. Now we all, by nature inherited from Adam, reject the testimony of God and go about "knowing good and evil" for ourselves.

It is God's great condescension to continue to reveal Himself and to finally, fully reveal Himself in Jesus Christ. The very fact that Jesus had to come and show us the Father is testimony, not to the value of evidentiary witness, but to the depth of our need.

For the wrath of God is revealed from heaven against all ungodliness and unrighteousness of men, who by their unrighteousness suppress the truth. For what can be known about God is plain to them, because God has shown it to them. For his invisible attributes, namely, his eternal power and divine nature, have been clearly perceived, ever since the creation of the world, in the things that have been made. So they are without excuse. - Romans 1:18-20 

Personally, I was once blind but now I see. Now that I see, one of the clearest things I see is that I should have seen all along and so I do perceive others who did not need to be apprehended as dramatically as myself in order to believe as more blessed than I.

It is not wrong to seek after God because

"Then you will call upon me and come and pray to me, and I will hear you. You will seek me and find me, when you seek me with all your heart. - Jeremiah 29:12-13"

but seeking with a whole heart necessitates abandoning everything else. God wants us to seek after Him but the Scripture sets faith as the opposite of sin

"For whatever does not proceed from faith is sin. - Romans 14:23"

Since they are set at odds and we are trying to overcome the corruption of sinful flesh, it is logical that faith is the antidote rather than intellectual satisfaction.

There comes a point where a new birth is required (John 3) and this is not "of blood nor of the will of the flesh nor of the will of man, but of God. John 1:13b". If I may be so bold, for clarity, I would add 'nor of the intellect of man' although that is likely covered under 'flesh'. God is calling everyone to believe on the Lord and Savior Jesus Christ and be reconciled.

Jesus Christ is the only way to God.

“I am the way, and the truth, and the life. No one comes to the Father except through me. - John 14:6

And God has only one way of drawing folks to Jesus:

For the word of the cross is folly to those who are perishing, but to us who are being saved it is the power of God. For it is written, “I will destroy the wisdom of the wise, and the discernment of the discerning I will thwart.” Where is the one who is wise? Where is the scribe? Where is the debater of this age? Has not God made foolish the wisdom of the world? For since, in the wisdom of God, the world did not know God through wisdom, it pleased God through the folly of what we preach to save those who believe. For Jews demand signs and Greeks seek wisdom, but we preach Christ crucified, a stumbling block to Jews and folly to Gentiles, but to those who are called, both Jews and Greeks, Christ the power of God and the wisdom of God.  For the foolishness of God is wiser than men, and the weakness of God is stronger than men. - 1 Corinthians 1:18-25

A person needs to stop insisting that they would believe if only they had more proof. This makes disbelief to be God's fault. The problem isn't that men can't believe or don't believe. The problem is that we won't believe. We have been given all of the proof needed.

‘If they do not hear Moses and the Prophets, neither will they be convinced if someone should rise from the dead.’” - Luke 16:31

We are not required to have a 'leap of faith' : we do have evidence.

Thomas was given the opportunity to be one of the first to believe the report of Jesus' resurrection without having personally witnessed his physical presence.

Thomas chose, rather than believe the report of the chosen apostles of Jesus Christ that the Christ had arisen from the dead, to see for himself.

The others, also, did the same, when the two Marys and Joanna told the apostles of the Lord's resurrection :

And their words seemed to them as idle tales and they believed them not.

[Luke 24:11, KJV]

Thereafter, after the ascension of Jesus Christ, followers of Jesus Christ would need to accept the verbal or written report and would be unable to 'see for themselves'.

Just as we, now, must either receive the report of the apostolic documentation in scripture, or disbelieve altogether.

So Jesus tells Thomas that we who receive the report are blessed, having not seen.

Yet Thomas had the great privilege of being one of the original witnesses to the resurrection.

So none is left wanting.

We are all blessed, but in different ways.

We who believe now do not believe 'without evidence'. We have the reliable evidence of the apostolic record - scripture that is 'God-breathed' (Theopneustos) also translated as 'inspired' :

All scripture is given by inspiration of God, and is profitable for doctrine, for reproof, for correction, for instruction in righteousness:

[I Timothy 3:16, KJV]

And we who have not seen, and yet have believed, love the Lord Jesus :

Whom having not seen, ye love; in whom, though now ye see him not, yet believing, ye rejoice with joy unspeakable and full of glory:

[1 Peter 1:8, KJV]

We do have evidence. And we believe. And we love.

The evidence was supplied to us through faithful witnesses, one of whom was Thomas.

he would have to accept any word of mouth relating any miraculous claim that was supposedly witnessed by anyone ever

That's quite the extrapolation there. He was asked to believe what his core group of three years had seen, regarding the most important event in their lives, regarding their leader (that he had seen perform miracles). Not "any miraculous claim", not by "anyone", not "ever".

I'm going to assume that you don't dispute the basic facts of science, say physics, astronomy, etc. Have you done the math yourself? Have you done the experiments yourself? Of course not, and so you are trusting others (who are themselves respected by many), the scientists, on what they tell you. You trusted other people's testimony about most things your learned at school, you trust other people's testimony when you read the news, etc., etc.