Why will God send Jesus Christ back according to Acts 3:20?
God will send Jesus Christ back to fulfill the covenant and Kingdom promises—the times of refreshing from the Lord’s presence. Peter ties repentance and blotting out of sins to that future refreshing, then says God would send Jesus, previously preached to Israel, as the Second Coming, so He can be Israel’s living King.
Les explains that Acts 3:19-20 is one continuing thought: Peter calls Israel to repent and be converted so their sins may be blotted out when the times of refreshing come from the presence of the Lord. He points out that verse 19 does not end with a period but a semicolon, so the thought flows into verse 20: God would send Jesus Christ, whom they had previously heard preached. The purpose is to fulfill those covenant and Kingdom promises, and this sending is the Second Coming. Les notes Israel knew what Peter and the others had been preaching—that although they killed Him, God raised Him from the dead, and He can still be their King because He is alive.
And he shall send Jesus Christ, which before was preached unto you: