1 Thessalonians 4:15-17 - how do we judge the credibility of Paul as he thought the world would come to an end during his lifetime?

See https://biblehub.com/commentaries/1_thessalonians/4-15.htm

Opinions are not unanimous, but the idea is widespread among commentators that Paul did not place himself with certainty but merely with hope among those who would be alive when Christ returns. So how should we judge Paul? As an optmimist - not a false prophet. Take Paul's hope together with this prophecy in Acts 21:

10 After we had been there a number of days, a prophet named Agabus came down from Judea. 11 Coming over to us, he took Paul’s belt, tied his own hands and feet with it and said, “The Holy Spirit says, ‘In this way the Jewish leaders in Jerusalem will bind the owner of this belt and will hand him over to the Gentiles.’”

Combine the blessed hope of meeting Christ while alive with the prophecy that continued faithful service will lead to imprisonment and death, and you get a picture of a man of courage and faith, who like Job refused to let go of the Word of God even if God slays him, and was content to be struck down rather than abandon his savior.

Benson Commentary:

It is well observed, says Whitby, by the Greek scholiasts, that the apostle speaks these words, not of himself, but of the Christians that should be found alive at the second coming of Christ: so Chrysostom, Theodoret, Œcumenius, and Theophylact; for he well knew that he was not to live till the resurrection

Barnes Notes:

From this expression, it would seem, that some of the Thessalonians supposed that Paul meant to teach that he himself, and many of the living, would survive until the coming of the Lord Jesus, and, of course, that that event was near at hand. That this was not his meaning, however, he is at special pains to show in 2 Thessalonians 2:1-10.

Gill's Exposition of the Entire Bible:

That we which are alive, and remain unto the coming of the Lord: not that the apostle thought that he and the saints then in the flesh should live and continue till the second coming of Christ; for he did not imagine that the coming of Christ was so near, as is manifest from 2 Thessalonians 2:1 though the Thessalonians might take him in this sense, which he there corrects; but he speaks of himself and others in the first person plural, by way of instance and example, for illustration sake; that supposing he and others should be then in being, the following would be the case: and moreover, he might use such a way of speaking with great propriety of other saints, and even of those unborn, and that will be on the spot when Christ shall come a second time; since all the saints make up one body, one family, one church and general assembly; so that the apostle might truly and justly say, "we which are alive"; that is, as many of our body, of our family, of our church or society, that shall be living at the coming of Christ; and he might choose the rather to speak in this form, person, and tense, to awaken the care, circumspection, diligence, and watchfulness of the saints, since it could not be known how soon the Lord would come: however, from hence it appears, that there will be saints alive at Christ's second coming; he will have a seed to serve him till he comes again; he always had in the worst of times, and will have, and that even in the last days, in the days of the son of man, which are said to be like those of Noah and of Lot: and these are said to "remain", or to be "left", these will be a remnant, the residue and remainder of the election of grace, and will be such as have escaped the fury of antichrist and his followers, or of the persecutors of the saints

Geneva Study Bible:

He speaks of these things, as though he should be one of those whom the Lord will find alive at his coming, because the time of his coming is uncertain: and therefore every one of us ought to be in such a readiness, as if the Lord were coming at any moment.

Meyer's NT Commentary:

Meyer Lists the names of commentators who argued that Paul referred to the latter church as a collective, which may or may not include him as a survivor to the time of Christ's return:

Chrysostom, Theodoret, John Damascenus, Oecumenius, Theophylact, Erasmus, Castalio, Calvin, Musculus, Bullinger, Zanchius, Hunnius, Balduin, Vorstius, Cornelius a Lapide, Jac. Laurentius, Calixt, Calov, Joach. Lange, Whitby, Benson, Bengel, Flatt...

Cambridge Bible for Schools and Colleges:

that we which are alive and remain unto the coming of the Lord - This should be: we that are alive, that remain (or survive) unto the coming of the Lord. The second designation qualifies the first,—“those (I mean) who survive till the Lord comes.” St Paul did not count on any very near approach of the second Advent: comp. 2 Thessalonians 2:1-2. At the same time, his language implies the possibility of the great event taking place within his lifetime, or that of the present generation. This remained an open question, or rather a matter on which questioning was forbidden

Pulpit Commentary:

That we which are alive and remain unto the coming of the Lord. These words are the occasion of an important discussion. It has been affirmed that the apostle here asserts that he himself expected to be alive, with the majority of those to whom he was writing, at the Lord's advent; that, according to his expectation, Christ's second coming was close at hand. "Those who are alive and remain" are distinguished from "those who are asleep," and in the former class the apostle includes himself and his readers. And a similar declaration is contained in the First Epistle to the Corinthians: "We shall not all sleep, but we shall all be changed" (1 Corinthians 15:51). Such is the view adopted by Grotius, Olshausen, Koch, Neander, Lechler, Baur, Winer, Reuse, Lunemann, Riggenbach; and, among English divines, by Alford, Jowett, Stanley, and Conybeare. Some of them suppose that Paul changed his opinion on this point - that whilst in his earlier Epistles he taught the immediateness of the advent, in his later Epistles he renounced this hope and looked forward to his own departure. There does not seem to be any ground for this opinion. On the contrary, it would appear from the Second Epistle to the Thessalonians, written only a few weeks after this Epistle, that Paul did not expect the advent immediately, but mentions a series of events which would intervene before its occurrence (2 Thessalonians 2:1-3). And in this Epistle he represses the curiosity of the Thessalonians about the precise time of the advent by telling them that it was beyond the sphere of his teaching (1 Thessalonians 5:1, 2). We consider, then, that the apostle speaks here as a member of the Christian body, and uses a very common form of expression - that we Christians which are alive and remain unto the coming of the Lord; but not at all intending to express his confidence that he himself and his converts would be actually alive at the advent. "He spake," says St. Chrysostom, "not of himself, but of Christians who would be alive at the day of judgment." Such is the view adopted by Chrysostom, Calvin, Bengel, Hofmann, Lunge, Macknight, Ellicott, Bishop Alexander, Wordsworth, and Vaughan.