John Calvin Commentary Acts 3:17

"And now, brethren, I know that in ignorance ye did it, as did also your rulers." — Acts 3:17 (ASV)

Because it was feared that, being overwhelmed by despair, they might reject his teaching, he lifts them up a little. We must moderate our sermons so that they benefit the hearers, because unless some hope of pardon remains, the terror and fear of punishment hardens men’s hearts with stubbornness. For what David says is true: That we fear the Lord when we perceive that he is unto us favorable, and easy to be pacified (Psalms 130:4).

Thus Peter lessens the sin of his nation due to their ignorance. For it would have been impossible for them to bear the weight of this realization if they had knowingly and willingly denied the Son of God and delivered him to be killed. Yet he does not flatter them when he says that they did it through ignorance; he only somewhat softens his speech, so that they would not be overwhelmed and swallowed up by despair.

Again, we must not interpret these words as if the people sinned simply out of ignorance, for under this lay hidden hypocrisy. Instead, as wickedness or ignorance abounds, the action is characterized by one or the other. Therefore, Peter’s meaning is that they did it more through error and a blind zeal than through any deliberate wickedness. But a question may be raised here: if any person has offended knowingly and willingly, will he inevitably fall into despair or not?

I answer that he does not, in this place, mention every kind of sin, but only the denying of Christ and the extinguishing of the grace of God, as far as it was in their power to do so. If anyone desires to know more concerning this, he may read the first chapter of the First Epistle to Timothy (1 Timothy 1:13).

As did also your rulers. First, this seems to be an inappropriate comparison, for the scribes and priests were carried away recklessly by an astonishing madness and were full of wicked unfaithfulness; but a perverse study of the law and zeal for it incited the people. Again, the people were incensed against Christ, since their rulers provoked them to it.

I answer that they were not all of one mind, for undoubtedly many of them were like Paul, to whom that truly applies which he writes elsewhere of the princes and rulers of this world: if they had known the wisdom of God they would never have crucified the Lord of glory. Therefore, he does not speak generally of all the rulers; but if any of them are curable, he invites them to repentance.