1 Peter 3:21

Likewise in the time after the cleansing of sin, there were three divisions: the building of the Ark, the showing of the rainbow, and the separation of tongues. For a hundred years, Noah worked on the Ark in which he was saved together with seven …

The water of the flood is a type of baptism because it both punished evil people and saved the good, just as baptism expels evil spirits and saves those who turn to Christ. This shows the great power of baptism, and how much we need …

Not the removal of the filth of the flesh, etc. For where is a good conscience, except where there is also unfeigned faith? For the apostle Paul teaches that the goal of the commandment is love from a pure heart, and a good conscience, and …

Through the resurrection of Jesus Christ, etc. For just as He, rising from the dead, ascended into heaven and sits at the right hand of God, so also has He, through baptism, marked the way of salvation and the entrance to the heavenly kingdom open …

The connection is as follows: so also baptism, which corresponds to this figure, now saves us, not as a removal of bodily filth, but as an appeal or earnest request for a good conscience before God. For those who are conscious of good in themselves, …

The antitype whereof - The thing typified by the ark, even baptism, now saveth us - That is, through the water of baptism we are saved from the sin which overwhelms the world as a flood: not, indeed, the bare outward sign, but the inward grace; a divine consciousness that both our persons and our actions are accepted through him who died and rose again for us.

The like figure whereunto even baptism doth also now save us,....

The like figure whereunto, even baptism, doth also now save us - There are some various readings here in the Greek text, but the sense is not essentially varied. Some have proposed to read (ῷ hō) to which instead of (ὅ ho) which, so as to make the sense “the antitype to which baptism now also saves us.” The antecedent to the relative, whichever word is used, is clearly not the ark, but water; and the idea is, that as Noah was saved by water, so there is a sense in which water is made instrumental in our salvation.

As Christ's death unto sin is the source of the believer's death unto, and so deliverance from, sin's penalty and power; so His resurrection life is the source of the believer's new spiritual life.

The like figure whereunto, etc. - Dr. Macknight has translated this verse so as to make the meaning more clear: By which (water) the antitype baptism (not the putting away of the filth of the flesh, but the answer of a good conscience towards God) now saveth us also, through the resurrection of Jesus Christ. He remarks that the relative ᾡ being in the neuter gender, its antecedent cannot be κιβωτος, the ark, which is feminine, but ὑδωρ, water, which is neuter. There are many difficulties in this verse; but the simple meaning of the place may be easily apprehended. Noah believed in God; walked uprightly before him, and found grace in his sight; he obeyed him in building the ark, and God made it the means of his salvation from the waters of the deluge. Baptism implies a consecration and dedication of the soul and body to God, the Father, Son, and Holy Spirit. He who is faithful to his baptismal covenant, taking God through Christ, by the eternal Spirit, for his portion, is saved here from his sins; and through the resurrection of Christ from the dead, has the well-grounded hope of eternal glory. This is all plain; but was it the deluge, itself, or the ark, or the being saved by that ark from the deluge, that was the antitype of which St. Peter speaks? Noah and his family were saved by water; i.e. it was the instrument of their being saved through the good providence of God. So the water of baptism, typifying the regenerating influence of the Holy Spirit, is the means of salvation to all those who receive this Holy Spirit in its quickening, cleansing efficacy. Now as the waters of the flood could not have saved Noah and his family, had they not made use of the ark; so the water of baptism saves no man, but as it is the means of his getting his heart purified by the Holy Spirit, and typifying to him that purification. […]