Albert Barnes Commentary Acts 3:18

"But the things which God foreshowed by the mouth of all the prophets, that his Christ should suffer, he thus fulfilled." — Acts 3:18 (ASV)

But those things. Namely, those things that actually occurred, pertaining to the life and death of the Messiah.

Had shown. Had announced, or foretold.

By the mouth of all his prophets.

That is, by the prophets in general, without affirming that each individual prophet had a distinct prediction concerning this. The prophets taken together, or the prophecies as a whole, had declared this. The word “all” is often used in this somewhat limited sense (Mark 1:37; John 3:26). In regard to the prophecies concerning Christ, see the notes on Luke 24:27.

Has so fulfilled. He has caused to be fulfilled in this manner; that is, by the rejection, denial, and wickedness of the rulers. It has turned out to be in strict accordance with the prophecy. Peter uses this fact in exhorting them to repentance, but it is not to be regarded as an excuse for their sins. The mere fact that all this was foretold, that it was in accordance with the purposes and predictions of God, does not take away the guilt of it, or constitute an excuse for it. In regard to this, we may remark:

1. The prediction did not change the nature of the act. The mere fact that it was foretold, or foreknown, did not change its character. See the notes on Acts 2:23.
2. Peter still regarded them as guilty. He did not urge the fact that this was foreknown as an excuse for their sin, but to show them that since all this happened according to the prediction and the purpose of God, they had hope in his mercy. The plan was that the Messiah should die to make a way for pardon; and, therefore, they might have hope in his mercy.
3. This was a notable instance of the power and mercy of God in overruling the wicked conduct of men to further his purposes and plans.
4. All the other sins of men may thus be overruled, and thus the wrath of man may be made to praise him. But,
5. This will constitute no excuse for the sinner. It is no part of his intention to honor God, or to advance his purposes; and there is no direct tendency in his crimes to advance his glory. The direct tendency of his deeds is counteracted and overruled; and God brings good out of the evil. But this surely constitutes no excuse for the sinner.

If it is asked why Peter insisted on this, if he did not mean that it should be regarded as an excuse for their sin, I reply, that it was his design to prove that Jesus was the Messiah; and having proved this, he could assure them that there was mercy. Not because they had not been guilty; not because they deserved favor; but because the fact that the Messiah had come was an argument that any sinners might obtain mercy, as he immediately proceeds to show them.