21 The like figure whereunto even baptism doth also now save us (not the putting away of the filth of the flesh, but the answer of a good conscience toward God,) by the resurrection of Jesus Christ:
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,
21 The waters of baptism do that for you, not by washing away dirt from your skin but by presenting you through Jesus' resurrection before God with a clear conscience.
21 There is also an antitype which now saves us--baptism (not the removal of the filth of the flesh, but the answer of a good conscience toward God), through the resurrection of Jesus Christ,
21 And that water is a picture of baptism, which now saves you, not by removing dirt from your body, but as a response to God from a clean conscience. It is effective because of the resurrection of Jesus Christ.
Matthew Henry's Commentary on 1 Peter 3:21
Commentary on 1 Peter 3:14-22
(Read 1 Peter 3:14-22)
We sanctify God before others, when our conduct invites and encourages them to glorify and honour him. What was the ground and reason of their hope? We should be able to defend our religion with meekness, in the fear of God. There is no room for any other fears where this great fear is; it disturbs not. The conscience is good, when it does its office well. That person is in a sad condition on whom sin and suffering meet: sin makes suffering extreme, comfortless, and destructive. Surely it is better to suffer for well-doing than for evil-doing, whatever our natural impatience at times may suggest. The example of Christ is an argument for patience under sufferings. In the case of our Lord's suffering, he that knew no sin, suffered instead of those who knew no righteousness. The blessed end and design of our Lord's sufferings were, to reconcile us to God, and to bring us to eternal glory. He was put to death in respect of his human nature, but was quickened and raised by the power of the Holy Spirit. If Christ could not be freed from sufferings, why should Christians think to be so? God takes exact notice of the means and advantages people in all ages have had. As to the old world, Christ sent his Spirit; gave warning by Noah. But though the patience of God waits long, it will cease at last. And the spirits of disobedient sinners, as soon as they are out of their bodies, are committed to the prison of hell, where those that despised Noah's warning now are, and from whence there is no redemption. Noah's salvation in the ark upon the water, which carried him above the floods, set forth the salvation of all true believers. That temporal salvation by the ark was a type of the eternal salvation of believers by baptism of the Holy Spirit. To prevent mistakes, the apostle declares what he means by saving baptism; not the outward ceremony of washing with water, which, in itself, does no more than put away the filth of the flesh, but that baptism, of which the baptismal water formed the sign. Not the outward ordinance, but when a man, by the regeneration of the Spirit, was enabled to repent and profess faith, and purpose a new life, uprightly, and as in the presence of God. Let us beware that we rest not upon outward forms. Let us learn to look on the ordinances of God spiritually, and to inquire after the spiritual effect and working of them on our consciences. We would willingly have all religion reduced to outward things. But many who were baptized, and constantly attended the ordinances, have remained without Christ, died in their sins, and are now past recovery. Rest not then till thou art cleansed by the Spirit of Christ and the blood of Christ. His resurrection from the dead is that whereby we are assured of purifying and peace.