Peter gives a speech where he makes three key points:
1) He boldly claims that Jesus is the Messiah foretold in Jewish scripture, who God "raised up" and sent as his "Servant" to bless people.
2) Jesus turns people away from their sins by appealing to their love for God and revealing God's goodness, rather than threatening punishment.
3) Peter's understanding is growing that the blessing Jesus brings is meant not just for Jews but for people of all nations, as the Old Testament promised. However, Jews will be the first to receive this blessing.