Peter used corresponding to that, a phrase containing the word antitupon, which means “copy,” “counterpart,” or “figure pointing to” to make the transition to the salvation in Christ. That word yielded the theological term antitype, which in the New Testament describes an earthly expression of a heavenly reality—a symbol or analogy of a spiritual truth (cf. John 3:14–16; Heb. 4:1–10; 8:2, 5). The preservation in the ark of those who believed God is analogous to the salvation believers have in Christ.
Some commentators believe the Flood is the antitype because antitupon (v. 21) and hudatos (water, v. 20) are both neuter nouns. But it is better to view the antitype in the broader sense of Noah and his family’s total experience with the ark. God preserved them from the flood waters while the rest of mankind perished. Noah and his children are a genuine type of the salvation in Jesus Christ, which preserves believers safely through God’s judgment on sinners. . . .