“gates of hell”: πυλαι αδου, a somewhat peculiar
phrase that only appears in Mt 16:18. Nevertheless, it has a specific meaning
in this context. It is first necessary to understand what is meant by the
translation “hell.” In Mt 16:18 “hell” is the Greek word αδης (hades). It appears 11 times in the NT. In some passages, hades
refers to the place of punishment of the wicked (Mt 11:23; Lk 10:15;
16:23). At other times “death” and “hades” are coupled together (Ap 1:18; 6:8;
20:13-14). In other places it refers to death or the place of the dead (Ac
2:27, 31; 1Co 15:55). (NB: The occurrence in 1Co 15:55 is according to the
textual variant found in ℵc Ac
K P Y 88 104 et al, Origen, Athanasius, Epiphanius, Chrysostom,
Eutherius, Theodoret. Otherwise, the reading is θανατε (“death”) found in P46 ℵ B C D (Dc omits θανατε) G, Irenaeus, Origen, Eusebius, Theodoret, et al). Hades is
used for both “hell” and “death” because, prior to the death and resurrection
of Christ, it was the place where the unrighteous were detained immediately after
death. Its usage was identical to the Hebrew word שׁאול (sheol), which referred
to either “hell” or the “grave” (cf. Dt 32:22; Ps 9:17; Is 5:14; 14:15; Gn
37:35; 1Kg 2:6; Hs 13:14). When referring specifically to the judgment of
eternal hell, the NT uses a different word, γεεννα (gehenna), appearing 12× (Mt 5:22,29,30; 10:28; 18:9; 23:15,33;
Mk 9:43,45,47; Lk 12:5; Jm 3:6)). In regard to Mt 16:18’s phrase “gates of
hell,” the word “gates” suggests certain people are prevented from going beyond
the gates, and certain people are prohibited from entering through the gates,
which is why Ap 1:18 states the resurrected Christ has the “keys of death and
hades,” since it is he who detains the souls present there. (Robert A.
Sungenis, Commentary on the Catholic Douay-Rheims New Testament from the
Original Greek and Latin, 4 vols. [State Line, Pa.: Catholic Apologetics
International Publishing, Inc., 2022], 1:355 n. 224)