It’s a scene you hopefully know well: At the beginning of Jesus’ ministry, Jesus has St. John the Baptist baptize him, after which the Holy Spirit comes down on Jesus like a dove and the Father’s voice is heard. (cf. Matthew 3, Mark 1, Luke 3)
Which may have left you confused. Baptism is for the forgiveness of sins, but Jesus never sinned – so why was he getting baptized?
The first thing to know is that Jesus did not receive the Sacrament of Baptism. The baptism of St. John the Baptist was only symbolic for repentance, whereas Christian baptism actually affects the grace of forgiveness.
Still, Jesus did not need to repent of anything. So what was he doing? The answer shows the radical nature of Christ’s ministry: He was turning baptism into a Sacrament. (ST III.39.1-2)
Here’s why this is so radical.
Normally, in the Old Testament unclean things make other things unclean when they come into contact. Holy things need to be kept separate so as to not be defiled.
Christ, of course, has no need for sanctification. Rather, it is he who sanctifies others. So when Christ received the baptism of John, instead of Jesus being sanctified, the
