What did Peter tell Israel to do in order to have their sins blotted out?
Peter told the nation of Israel to repent and be converted, so that their sins may be blotted out and times of refreshing may come from the presence of the Lord. This call was given to Israel as a nation, with the promise attached to their repentance and conversion.
Les explains that Peter, speaking to the nation of Israel in verse 19, said, “Repent ye therefore, and be converted, that your sins may be blotted out, and the times of refreshing shall come from the presence of the Lord.” Les emphasizes that this was a message to Israel as a nation, not a period but a semicolon, because verse 20 continues the same thought: God shall send Jesus the Christ, whom heaven must receive until the times of restitution of all things. Even though Peter expected the Lord’s immediate return to Israel if they would repent, Les points out that Peter also recognizes they would have to go through the seven years of restitution of all things. Israel had rejected their Messiah in ignorance, but now Peter calls them to repentance and conversion so their sins could be blotted out.