Did God forgive sins based on Jesus' future sacrifice?

Jesus forgave sins as he was the son of God with the authority to do so John 1:1 The Sacrifice on the cross wasn't necessarily for the explicit purpose of forgiving sins but rather to restore man to where we were meant to be in relation to God. Prior to the cross, Sin and Death had dominion over man and it is from this the Cross (the sacrifice saved us) Romans 8:1 There is therefore now no condemnation for those who are in Christ Jesus who walk not after the flesh but after the spirit - Romans 8:2 for the law of the spirit of Life in Christ Jesus has set us free from the Law of sin and death. The sacrifice of the Cross didn't begin Jesus's power but rather extended it to include us.

My understanding of scripture is that Jesus forgave sins based on the authority of his future sacrifice, as you stated in your question.

Reason given:

1 Corinthians 15:17 And if Christ be not raised, your faith is vain; you are yet in your sins

And later we see:

1 Corinthians 15:22-23 For as in Adam all die, even so in Christ shall all be made alive. But every man in his own order: Christ the firstfruits; afterward they that are Christ's at his coming.

The people whom Christ healed would die. His promise of forgiveness would come into effect at the first resurrection. Their sins forgiven, they would be raised from the dead.

1 Thesalonians 4:16-17 For the Lord himself shall descend from heaven with a shout, with the voice of the archangel, and with the trump of God: and the dead in Christ shall rise first: Then we which are alive and remain shall be caught up together with them in the clouds, to meet the Lord in the air: and so shall we ever be with the Lord.

At that point the forgiveness of sins comes into effect, in the resurrection to eternal life, because of Christ's sacrifice.

This is a contentious issue. Most notably, if for not other reason, than that it lies at some of the root of the difference between Protestants and Catholics.

Again Jesus said, "Peace be with you! As the Father has sent me, I am sending you." And with that he breathed on them and said, "Receive the Holy Spirit. If you forgive anyone’s sins, their sins are forgiven; if you do not forgive them, they are not forgiven."

John 20:21-23

Considering the verse above, there is actually a dispensation given to believers to forgive sins.

Now, before anyone goes off on any particular tangent, I believe there are many ways this comes about, but that they all point to Christ's sacrifice in the end.

Just as there are many different formulas for healing in the New Testament (in James, it is the elders anointing with oil and the prayer of faith, in the sending of people, it is the laying on of hands, in other places, it was faith, in others, the power of God present to heal). So, too, I see a variety of 'formulas' to bring about forgiveness. None are required, any will work.

When Jesus saw their faith, he said to the paralyzed man, “Son, your sins are forgiven.”

Now some teachers of the law were sitting there, thinking to themselves, “Why does this fellow talk like that? He’s blaspheming! Who can forgive sins but God alone?”

Immediately Jesus knew in his spirit that this was what they were thinking in their hearts, and he said to them, “Why are you thinking these things? Which is easier: to say to this paralyzed man, ‘Your sins are forgiven,’ or to say, ‘Get up, take your mat and walk’? But I want you to know that the Son of Man has authority on earth to forgive sins.” So he said to the man, “I tell you, get up, take your mat and go home.”

Mark 2:5-11

Going with the understanding that Jesus did everything as the Son of Man, and not the Son of God, it follows that he is speaking that a man, anointed by the Holy Spirit, can forgive sins. This would include believers, then.

Further, there is a rhetorical question. Which is easier? To forgive the man or heal him? The answer isn't given, but it seems to me that healing was easier.

What appears to be the case, however, is that, through the agency of the Holy Spirit, a believer can forgive sins, as well as heal the sick, cast out demons, and raise the dead. This of course points to Christ, as all forgiveness would.

With Christ Himself, of course, it would partly be of the virtue of Him being sinless, in the same way that He received the Holy Spirit in the first place (a well-pleasing Son). Once anointed, it was His calling to do so, as led by the Father (remembering that John had already prepared the way through repentance). However, this dispensation, in subjection to the will of the Father, was part of the calling, as described.

For us, we enter into that same perfection through His sacrifice, and participate in the same. Albeit, just as with healing, it is not apparent that it is necessary that forgiveness come through another person (say, a priest), but that it can. This forgiveness, then, too, would be said to come from Christ and His sacrifice, ultimately.

The notion that only God can forgive sins, however, seems directly what Jesus was saying wasn't the case in Mark 2:6-9.

Did God forgive sins based on Jesus" future sacrifice?

Salvation is a function of faith.

Ephesians 2:8-9 For by grace are ye saved through faith; and that not of yourselves: it is the gift of God: Not of works, lest any man should boast.

It is our new life in Christ which obliterates our sin.

Ephesians 2:5 Even when we were dead in sins, hath quickened us together with Christ, (by grace ye are saved;)

Colossians 2:13 And you, being dead in your sins and the uncircumcision of your flesh, hath he quickened together with him, having forgiven you all trespasses;

Those with faith in the Old Testament times did not receive the indwelling of the Holy Spirit;

Hebrews 11:39-40 And these all, having obtained a good report through faith, received not the promise: God having provided some better thing for us, that they without us should not be made perfect.

In Old Testament times as today sin separates us from God.

Isaiah 59:2-4 But your iniquities have separated between you and your God, and your sins have hid his face from you, that he will not hear. For your hands are defiled with blood, and your fingers with iniquity; your lips have spoken lies, your tongue hath muttered perverseness.
None calleth for justice, nor any pleadeth for truth: they trust in vanity, and speak lies; they conceive mischief, and bring forth iniquity.

The picture we get of the forgiveness of sins in the Old Testament is one that might be called, "batch processing".

Ezekiel 18:24 But when the righteous turneth away from his righteousness, and committeth iniquity, and doeth according to all the abominations that the wicked man doeth, shall he live? All his righteousness that he hath done shall not be mentioned: in his trespass that he hath trespassed, and in his sin that he hath sinned, in them shall he die.

Forgiveness seems available to those who were inclined to ask;

Psalm 86:5 For thou, Lord, art good, and ready to forgive; and plenteous in mercy unto all them that call upon thee.

Luke 18:13-14 And the publican, standing afar off, would not lift up so much as his eyes unto heaven, but smote upon his breast, saying, God be merciful to me a sinner. I tell you, this man went down to his house justified rather than the other: for every one that exalteth himself shall be abased; and he that humbleth himself shall be exalted.

There did seem to be a way to accrue righteousness through faith.

Hebrews 11:33 Who through faith subdued kingdoms, wrought righteousness, obtained promises, stopped the mouths of lions,

James 2:23 And the scripture was fulfilled which saith, Abraham believed God, and it was imputed unto him for righteousness: and he was called the Friend of God.

We know that some of those in Israel will receive eternal life.

Daniel 12:2 And many of them that sleep in the dust of the earth shall awake, some to everlasting life, and some to shame and everlasting contempt.

It may be that in contrast to us who have eternal life as the result of faith now, the Old Testament saints receive their eternal life at their resurrection.

John 5:24 Verily, verily, I say unto you, He that heareth my word, and believeth on him that sent me, hath everlasting life, and shall not come into condemnation; but is passed from death unto life.

It may be that the reception of eternal life is the judicial act that blots out our sins. Christians receive it when they trust in Jesus and Old Testament saints receive it when they are resurrected.

There is another type of sin forgiveness that can cause confusion. There is the judicial forgiveness of all sins that is associated with salvation. There is also a functional forgiveness that reestablishes relationship.

1 John 1:9 If we confess our sins, he is faithful and just to forgive us our sins, and to cleanse us from all unrighteousness.

Here forgiveness is contingent upon our act of confession "h*m* logos". If we are able to say the "same words" about our sin that God would, we bring ourselves into alignment with truth and are able to have fellowship with God restored. This may be more representative of the forgiveness of sins described on the Old Testament.

The forgiveness of sins associated with salvation may be an effect rather than a cause and therefore more closely associated with the cross.

The forgiveness of sins, batch of sins, even consequence of sin that figures so prominently in the Old Testament and the ministry of Jesus may be more associated with the will of the Creator, within his purview, and expressive of His mercy. The forgiveness of sins and subsequent removal of malady was more reflective of the bona fides of Jesus as creator than as Redeemer.

John 1:3 All things were made by him; and without him was not any thing made that was made.