This is an act of faith following repentance. This is the biblical pattern. In Acts 8:36-38 we read: " Now as they went down the road, they came to some water. And as the eunuch said, "See, here is the water. What hinders me from being baptized?" Then Philip said, 'If you believe with all your heart, you may.' And he answered and said, 'I believe that Jesus Christ is the son of God.' So he commanded the chariot to stand still. And both Philip and the eunuch went down into the water, and he baptized him." Jesus commanded water baptism in Matthew 28:19: " Go therefore and make disciples of all nations, baptizing them in the name of the Father and of the Son and of the Holy Spirit." Jesus Himself is an example of being baptized, which is recorded in Matthew 3:13-15.