Peter assured Christians of their eternal security by faith in Christ. He did so, by reminding them that their election was manifested precisely "unto obedience and sprinkling of the blood of Jesus" (First Epistle 1:2).
Peter’s First Epistle (3:18f) went on to remind Christians that Christ has suffered for sins once and for all, so that He might bring us to God. The longsuffering of God waited in the days of Noah, while the ark was being prepared — in which eight persons were delivered through water. Baptism, the antitype of this, delivers us now.