What does 1 Peter 3:21 mean?
Peter has just concluded several difficult-to-understand verses with a reference to the ark of Noah. In this craft, eight people were "brought safely through the water." In this verse, he writes that baptism corresponds to the water of Noah's flood.This is also a controversial verse. Bible scholars offer differing interpretations of it. Part of the issue is that the New Testament clearly and repeatedly teaches that salvation from hell comes only through faith in Christ, by God's grace (Ephesians 2:8–9). Christians were expected, even commanded, to be baptized. However, the act of baptism is an expression of faith and obedience, not the means of salvation. (See Colossians 2:12; Galatians 3:27; Romans 6:3–5.) Is Peter contradicting that idea when he writes that baptism now saves us?
Clearly, based on his other writings, Peter is not suggesting that the mechanical act of being baptized is what makes a person saved for eternity. Instead, taking the verse as a whole, he seems to be saying that the resurrection of Jesus Christ from the dead saves us. It is this resurrection which Christians publicly express their faith in when being baptized. This is supported by Peter's inclusion of the phrase "which corresponds to this," suggesting a parallel, rather than an identical purpose.
Another possible reading is that the word "saves" doesn't refer to eternal salvation, at all. Instead, by this view, Peter is saying that the act of publicly identifying ourselves with Christ, through baptism, saves us from being tempted to hide our faith to avoid the suffering and persecution of Christians Peter has been addressing.
In any case, this water baptism is not about making a person clean in their flesh. It's about asking God for a good conscience, or standing identified with God with a good conscience. In 1 Peter 3:16, Peter wrote that Christians should live in the world with a good conscience so that nobody can have a valid reason for accusing us of doing anything wrong. The act of being publicly baptized was part of establishing that good conscience with God and before a watching world.
And, again, as the final phrase of the verse states, this is all made possible through the resurrection of Jesus from the dead that reveals the power of God to give eternal life.