In the Old Testament, the Lord insisted that his people undergo washings in a variety of circumstances (Exodus 29:4; Leviticus 14:8; Leviticus 17:15; Ezekiel 36:25). The washing was needed because of impurity from sin. The same concept appears in the baptism of John for the forgiveness of sins (Matthew 3:6). On the day of Pentecost, Peter called on the crowds to repent and be baptized…for the forgiveness of your sins
(Acts 2:38). That Peter wants his readers to hear this meaning as they read the word baptism
in the present text is demonstrated by his further words, not as a removal of dirt from the body,
which imply that he is thinking of a removal of dirt from the soul.
21 Baptism, which corresponds to this, now saves you, not as a removal of dirt from the body but as an appeal to God for a good conscience, through the resurrection of Jesus Christ,