There has been great debate over the years regarding what did Peter mean when he wrote this passage:
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 (1 Peter 3:21).
Notice, this verse says, "Baptism...now saves you." Many have said this confirms baptismal regeneration which some Christian denominations hold to. Does baptism save you or it is a confirmation of being saved?
To helps understand this verse, here is Gabe Hughes with another "When We Understand The Text" video:
Next, John Piper looks more intently into this passage along with verse 22: