Peter has no problem joining belief with water for salvation (Acts 2,10; 1 Peter 1-3). In this he is like his King and his fellow-apostles:
Go into all the world and proclaim the gospel to the whole creation. Whoever believes and is baptized will be saved, but whoever does not believe will be condemned (Mark 16:15-16).
… Christ loved the church and gave himself up for her, that he might sanctify her, having cleansed her by the washing of water with the word (Ephesians 5:25-26; see Hebrews 10:22).
… for in Christ Jesus you are all sons of God, through faith. For as many of you as were baptized into Christ have put on Christ (Galatians 3:26-27).
Faith and baptism go together for entering Christ and becoming “children of God.” This is true for “all” – everybody (John 3:3-5; Mark 16:15-16; Acts 2:38; Romans 6:3; Galatians 3:26-27). The King Himself sets the example, submitting to baptism like “all” others (Luke 3:21). Even one as sincere and special as Saul (Paul) must submit. For three days, after seeing the risen Christ, Saul fasts and prays. Do his faith and prayers alone cleanse him? No, for after these things God’s spokesman arrives, saying,
And now why do you wait? Rise and be baptized and wash away your sins, calling on his name (Acts 22:16).
His sins remain, and need to be washed away. Such forgiveness takes place when belief obeys in baptism. Truly, just as Jesus says, no one can enter the kingdom unless he is born through water and Spirit.