I posted this at another site a while back, thought I might post it here for consideration (given some recent postings).
The Fathers saw the "gates of hades" in a few things:
1) Wordly powers and persecutions. Saint John Chrysostom is the major figure who interpreted the phrase in this way. (cf Saint John Chrysostom, Homily 5 Against the Jews [or Judaizers], 2, 8 and Homily 21 on Hebrews)
2) Vice, sin, and death. Perhaps the most articulate description of the Gates of Hades being sin and vice and our own shortcomings was given by that heretic Origen (cf Commentary on the Gospel of Matthew, Book 12, 11-13). However, numerous other Fathers, and some of the Church's hymns, also see sin, vice, and ultimately death, as a "gate of hades". (cf Jerome as quoted by Thomas Aquinas in: Catena Aurea, Gospel of Matthew, Chapter 16; Gregory of Nyssa, Life of Macrina; The Monk Jonas, The Life of Saint Columban; Gildas, Works, 68; Typika Service, The Kontakion of the Resurrection, Fifth Tone)
3) Even if some Fathers held to the above two interpretations, though, all the Fathers universally saw the "gates of hades" as speaking of heretics, heresies, and their followers. Saint John Cassian, for instance, says that "the gates of hell are the belief, or rather the misbelief, of heretics." (John Cassian, Seven Books of John Cassian, 3, 12) and Saint John of Damascus said that against the Church "the gates of hell, the mouths of heretics, the machines of demons--for they will attack--will not prevail. They will take up arms but they will not conquer" (Homily on the Transfiguration) Similar quotes are found throughout the patristic record (and indeed, even in the records of Ecumenical Councils--cf Council of Chalcedon [4th Ecumenical Council], The Sentence of the Synod)
So the "gates of hades" are not some menacing, iron gates (like you might see in a horror film), but things that are truly scary: sin, persecution, and heresy. So how do we know if the gates have conquered a Local Church (or Patriarchate)? If we look to the Fathers, we can see numerous attributes mentioned that a group or person fighting against these gates has. If they lack these attributes, then there is cause for concern.
First, the Orthodox have Christ as their head. "The Church is unshaken, and ‘the gates of hell shall not prevail against it,’ according to the voice of the Saviour, for it has Him for a foundation" (Cyril of Alexandria, Commentary on Zacharias) "For the Church cannot be moved because it is known to have been founded on that most solid rock, namely, Christ the Lord" (Cassiodorus, Expositions in the Psalms, Psalm 45, 5)
Second, the Orthodox not only have truth incarnate (Christ) as their foundation, but have an intellectual and experiential knowledge of the truth. Augustine said: "Christ, you see, built his Church not on a man, but on Peter's confession. What is Peter's confession? 'You are the Christ, the Son of the living God.' There's the rock for you, there's the foundation, there's where the Church has been built, which the gates of the underworld cannot conquer" (John Rotelle, The Works of Saint Augustine, p. 327) Similarly, Ambrose said: "Faith, then, is the foundation of the Church, for it was not said of Peter's flesh, but of his faith, that 'the gates of hell shall not prevail against it.' But his confession of faith conquered hell." (Ambrose, The Sacrament of the Incarnation of Our Lord).
As Saint Athanasius said: "In Thy saints, who in every age have been well pleasing to Thee, is truly Thy faith; for Thou hast founded the world on Thy faith, and the gates of hell shall not prevail against it." (Commentary on Psalm 11; Cf Hilary of Poitiers, On The Trinity, 6, 36-37 and 2, 23) Essentially, the struggle is for each of us to be a cooperator in breaking down the gates of hades. Thus we can sing of the Theotokos: "Rejoice, only gate through which the Word alone has passed. Lady, by your childbearing, you have broken the bars and gates of hell." (Triodion, Fifth Week of Lent, Saturday Matins, Praises of the Theotokos, The Canon, Tone Four, Canticle Three) We can say with Athanasius that all God's saints (or saints in the making, as we sinner are) have a part to play in protecting the Church against the gates of hades.
