"Washing away one's sins must mean to "forgive their sins" in Baptism (Acts 22:16)."
The reason for the New Testament writers closely associating baptism with salvation is that partaking in such a ritual placed one at a much higher risk of being persecuted for the faith. Baptism was viewed as evidence of a person's willingness to undergo martyrdom for the Cause of Christ. It is representative of the changes that the Holy Spirit has begun to work in our hearts. These articles are of relevance to the discussion:
"I guess I can understand how they question the Sacrament of Confession as I don't see it explicitly in John 20:23. However, this is where the understanding of the Traditions is invaluable to me."
While certain aspects of the Roman Catholic seven sacraments are biblical, the idea that the grace of God can be imparted to us through rituals is unbiblical. Justification is not by works of righteousness, but by us placing our trust in Christ and His finished work on the cross (John 1:12; Romans 3:27-28; 4:2-8; Galatians 2:16; 21; Ephesians 2:8-9; 1 Timothy 1:16; etc.). Rituals do not contribute to our salvation. It is abundantly clear that the Roman Catholic Church has a man-centered theology. Scripture is oftentimes taken out of context. Philosophy is elevated far above proper biblical exegesis.