“Wot” (3:17) means to know (Gen. 21:26). But where’d Peter get the idea the Jews didn’t know what they were doing when they killed the Lord? From the Lord! (Lu. 23:34). They could have known they were crucifying their God, the prophets described Him so well, but they didn’t. So Peter reduced the charge against Israel from murder to man-slaughter (cf. Deut. 19:4-6). Murderers had to die (Num. 35:16) but manslayers could flee to a city of refuge (35:10-30).
Israel’s people didn’t know He was God because they didn’t know their Bibles (John 7:25-27 cf. Micah 5:2). Israel’s rulers didn’t know He was their Christ because He was from Galilee, and they thought no prophet could come from Galilee (John 7:52). But Jonah did (Jonah 1:1 cf. II Ki. 14:25 cf. Josh. 19:13-16 cf. Mt. 4:15).
If rulers sinned through ignorance, they too could be spared (Lev. 4:22ff), and if the whole congregation sinned through ignorance, the priest could offer a sacrifice for them as well (Lev. 4:13).
Peter said that God fulfilled the prophets in killing the Lord (Acts 3:18) because in early Acts here God was assuming responsibility for their guilt. That’s how He could offer this manslaughter charge. But when they rejected His offer, Acts 13:27 says that the Jews fulfilled the prophets in killing Him. That’s similar to how God imputed our sins to Christ on the cross (II Cor 5:19), but will impute them back to unbelievers if they don’t get saved (cf. Rom. 4:8).
“Ye” (Acts 3:19) is plural. Peter offered salvation to individual Jews in Acts 2:38, but here he is offering salvation to the nation. Remember, the nation of Israel had to be saved before God’s plan to reach the other nations could continue (Acts 1:8), because God planned to use Israel to reach the Gentiles, and He insists His representatives be saved.
As further proof the nation needed to be saved, when the nation didn’t get saved, Paul reminded them that Isaiah had predicted that the nation wouldn’t get saved (Acts 28:24-27). Paul also told them what God was doing about it, turning to the Gentiles (28:27,28). See that word “convert” in Acts 28:28? That’s what Peter was asking the Jews to do in Acts 3:19, but they didn’t repent.
Peter is still talking to the nation when he extends God’s offer to blot out their sins (Acts 3:19). That’s what individuals get when they get saved. If they don’t, their sins aren’t blotted out or covered (Neh. 4:5), but if they do, their sins are covered (Rom. 4:7). But God dealt with Israel as a nation, and the nation won’t get their sins blotted out until “the times of refreshing” come (Acts 3:19), i.e., the kingdom.
We see types of this when God forgave Israel every time they fell (Num. 14:19). If they sinned so badly that God let them be taken captive, they were to “repent” and He would forgive them (I Ki. 8:46-50). They didn’t repent in Peter’s day, when they were in captivity to Rome, but they’ll be in captivity again after the Rapture, this time to the antichrist. If they’ll “repent” in that day (Acts 3:19) God will forgive the nation. We see a type of that when they repented during the Babylonian captivity (Ps. 85:1,2).
But before the kingdom can come, something else had to come first. Peter was speaking on the day of Pentecost, but the feast of the Day of Atonement followed Pentecost. That didn’t stand for Christ’s death; Passover stood for that. The Day of Atonement stood for the day Israel would get the benefit of Christ’s death. We get that benefit when we believe (Rom. 5:1,11), but Israel won’t get that as a nation until they believe as a nation. When will that happen? At the Second Coming of Christ (Rom. 11:26,27).
The kingdom is called “the times of refreshing” due to verses like Isaiah 35:1-10 and Zechariah 14:20. The heaven “received” the Lord (Mark 16:19) and will continue to receive Him “until” then (Acts 3:20,21). “Restitution” (v. 21) means to restore what’s lost. Adam lost the right to live in paradise on earth, but the Lord will restore man’s right to do that. All the prophets spoke about this (Acts 3:21), but none of them spoke about God taking us to heaven in the rapture. That was part of the mystery given to Paul (Rom. 16:25).
Video available on YouTube: Murder or Manslaughter? – Acts 3:17-21