John Trapp on 1 Peter 3:21

Verſe 21. Baptiſme doth alſo now ſave] It is of permanent uſe; and effectuall to ſeal up ſalvation whenſoever a man believes and repents. Hence we are once baptized for all. See Epheſ. 5.26. Tit. 3.5. The Popes decrees ſay, That Confirmation is of more value then Baptiſme, and gives the holy Ghoſt more plentifully and effectually.

Not the putting away] That none bear himſelf bold upon his Chriſtendome: Unregenerate Iſrael is to God as Ethiopia, Amos 9.7. A man may goe to hell with baptiſmall water on his face.

But the anſwer] The Stipulation, or confident interrogation, [non-Latin text not transcribed]. ſuch as is that of the Apoſtle, Rom. 8.33, 34, 35. and of Jeremy pleading with God, Chap. 12.1, and reaſoning the cauſe with him. David from his circumciſion promiſed himſelf victory over that uncircumciſed Philiſtim, ſo may we from our baptiſme, againſt all ſpirituall wickedneſſes.