Peter preached to unrepentant heathen nations. Persons who were not baptized as children and were not believers. He instructed them: First, repent of your sinful ways radically, return to the Lord and then they should be baptized them and their children. The following verse in verse 39 is clear and should be read in the context: “For the promise is for you and for your children and for all who are far off, everyone whom the Lord our God calls to himself.”