Acts 3:17,18 - I know that you acted in ignorance

3:17

Peter now seems to mollify the accusation he has made against them. He addresses them as “fellow Israelites”, he is one of them, he has not cast them into outer darkness! Then he says that they acted in ignorance, and even includes the leaders in this. So even the priests and the Pharisees are included in this. Today there is a great reluctance to talk about sin, to tell people that they are sinners. And indeed there are many bad ways of doing this. However, that is not a Biblical approach. Here we see that Peter has told them plainly of their sin, namely handing Jesus over to be killed (3:13). Then he speaks of the greatness of God, and then a call to repentance. Peter convicts with hope.

3:18

Their act in handing Jesus over to be killed was terrible, “but this is how God ...” They acted, but God was in control, fulfilling His purposes. Through Christ the promises of the prophets were fulfilled. Peter then says that the prophets foretold that the Messiah must suffer. There are various Psalms where we find this, and Isaiah 53 is the most famous passage.