New City Catechism #45: Is baptism with water the washing away of sin itself?

Answer: No, only the blood of Christ and the renewal of the Holy Spirit can cleanse us from sin.

Scripture:
Luke 3:16 John answered them all, saying, “I baptize you with water, but he who is mightier than I is coming, the strap of whose sandals I am not worthy to untie. He will baptize you with the Holy Spirit and fire.”