Cleansing refers to baptism,1 the waters of baptism symbolizing the washing away of sins and the forgiveness of sins2 (Acts 22:16; Romans 6:1–14; 1 Corinthians 6:9–11; Ephesians 5:26; Colossians 2:11–13; Titus 3:5; Hebrews 10:22). Having been baptized, there is now an expectation that moral change must be seen in your life.3 However, the heretics have gone back to their former ways; they are not living in the light of their baptism. Peter argues that our baptism, the cleansing, and forgiveness of sins that we have received should motivate us to become more and more like the One who cleansed us. If we neglect moral growth and turn back to our former lives, we are so to speak slapping our Lord in the face.4 In short, a person who does not seek to grow in Christian moral character is still in pagan ignorance and has not made a clean break with their past.5
9 For whoever lacks these qualities is so nearsighted that he is blind, having forgotten that he was cleansed from his former sins.