I received the following question regarding I Corinthians 15:51:

How can Paul be speaking “secrets” that have not before been revealed when he says in Acts 26:22 that all he’s spoken is all that Moses & the prophets have declared?

Paul has only spoken of things that were revealed by Moses and the prophets up to the time when he speaks these words in Acts 26:22. This changes when he writes Ephesians, for there he speaks of a dispensation of the grace of God, a secret “which in other ages was not made known to the sons of men, as it has now been revealed by the Spirit to His holy apostles and prophets.” So at this point he definitely had spoken things unrevealed before, neither to Moses nor to the prophets.

The question, then, is what about when Paul says he is speaking secrets before Acts 26:22, as he does in Romans 11:25, 16:25; I Corinthians 2:7, 4:1, 15:51; and II Thessalonians 2:7? The fact is that, as we examine these, none of them has to do with an event or even a period of time that was never prophesied in the previous revelations of God. In Romans, he speaks of a partial blindness happening to Israel until the fullness of the Gentiles is come in. This is a facet of the Acts period never before revealed, but it is not a totally new thing that Moses and the prophets never said would come. I Corinthians speaks of a wisdom of God never before revealed, but this wisdom has nothing to do with a new period of time and a new activity of God never revealed before. The secret of I Corinthians 15 has to do with a secret about the coming resurrection at the start of the kingdom, but this resurrection was revealed before. The revelation is a new truth about it, not a totally new thing. II Thessalonians speaks of the secret of iniquity. This again is not a totally new thing never before revealed, but an aspect of iniquity that is secret.

So when Paul says he has not spoken anything but what Moses and the prophets said would come, he is speaking accurately. When he had revealed secrets, they had been secret aspects of things previously revealed. He had not spoken of any new event or time period that had never been revealed before when he had spoken these secrets. That did not happen until after Acts 26:22, at the time of the writing of the book of Ephesians.