After His resurrection, Jesus told His apostles that “repentance for forgiveness of sins would be proclaimed in His name to all the nations, beginning from Jerusalem” (Luke 24:47, emphasis added). Clearly, according to Jesus, forgiveness of sin from God is predicated upon repentance. That does make sense, as it would seem odd to think of God forgiving people who have no intention of turning from the behavior of which He is forgiving them. It would also seem odd for anyone to expect forgiveness from God—or from anyone for that matter—if they intended to continue the behavior for which they are asking forgiveness. If they did, they really wouldn’t be asking for forgiveness, but rather for a license to continue their offensive behavior.
Jesus’ post-resurrection words to the apostles about God’s forgiveness being predicated on human repentance were no surprise to them, because at least some of them had heard John the Baptist preach, as Scripture declares, “a baptism of repentance for the forgiveness of sins” (Mark 1:4; Luke 3:3, emphasis added). Specifically, John preached, “Repent, for the kingdom of heaven is at hand” (Matt. 3:2).
Beyond that, all of the apostles heard Jesus proclaim the identical message, that is, “Repent, for the kingdom of heaven is at hand” (Matt. 4:17). In order to be ready for the coming kingdom—over which a King would obviously reign—people who were not currently submitted to that king needed to change what they were doing and submit to that king.