Psalms 118:20

In this place, then, the gates of hades are spoken of; but in the Psalms the prophet gives thanks saying, "He who lifts me up from the gates of death that I may declare all your praises in the gates of the daughter of Zion." And from this we learn that it is never possible for anyone to be fit to declare the praises of God, unless he has been lifted up from the gates of death and has come to the gates of Zion. Now the gates of Zion may be conceived as opposed to the gates of death, so that there is one gate of death, dissoluteness, but a gate of Zion, self-control; and so a gate of death, unrighteousness, but a gate of Zion, righteousness, which the prophet shows forth saying, "This is the gate of the Lord, the righteous shall enter into it." And again there is cowardice, a gate of death, but courage, a gate of Zion; and want of prudence, a gate of death, but its opposite, prudence, a gate of Zion. But to all the gates of the "knowledge that is falsely so called" one gate is opposed, the gate of knowledge which is free from falsehood. But consider if, because of the saying, "our wrestling is not against flesh and blood," etc., you can say that each power and world ruler of this darkness and each one of the "spiritual hosts of wickedness in the heavenly places" is a gate of hades and a gate of death. Let, then, the principalities and powers with which our wrestling is, be called gates of hades, but the "ministering spirits" gates of righteousness. […]

Let us therefore root this out quickly, and let us fall down before the Master and entreat him with tears, that he may show himself propitious and be reconciled to us and may restore us to the seemly and pure conduct that belongs to our love of the brothers. For this is a gate of righteousness opened to life, as it is written: "Open to me the gates of righteousness, that I may enter in thereby and praise the Lord. This is the gate of the Lord; the righteous shall enter in thereby." Seeing then that many gates are opened, this is that gate that is in righteousness, even that which is in Christ, whereby all are blessed who have entered in and direct their path in holiness and righteousness, performing all things without confusion. Let a person be faithful, let him be able to expound a deep saying, let him be wise in the discernment of words, let him be strenuous in deeds, let him be pure; for so much the more ought he to be lowly in mind, in proportion as he seems to be the greater; and he ought to seek the common advantage of all, and not his own.

Our father Jacob too prayed at Bethel and saw the gate of heaven opened, with a ladder going up on high. This is a symbol of our Savior that Jacob saw: the gate of heaven is Christ, in accordance with what he said: "I am the gate of life; every one who enters by me shall live forever." David too said, "This is the gate of the Lord, by which the righteous enter." Again, the ladder that Jacob saw is a symbol of our Savior, in that by means of him the just ascend from the lower to the upper realm. The ladder is also a symbol of our Savior's cross, which was raised up like a ladder, with the Lord standing above it; for above Christ is the Lord of all, just as the blessed apostle said: "The head of Christ is God." Now Jacob called that place Bethel; and Jacob raised up there a pillar of stone as a testimony, and he poured oil over it. Our father Jacob did this too in symbol, anticipating that stones would receive anointing—for the peoples who have believed in Christ are the stones that are anointed; just as John says of them: "From these stones God is able to raise up children for Abraham." For in Jacob's prayer the calling of the nations was symbolized.

But consider how the gates of righteousness are entered into. "These are the gates of the Lord" he saith, "the righteous shall enter into them" (ver. 20). At least let no wicked man enter there, that Jerusalem which receiveth not one uncircumcised, where it is said, "Without are dogs." Be it enough, that in my long pilgrimage "I have had my habitation among the tents of Kedar:" I endured even unto the end the intercourse of the wicked, but "these are the gates of the Lord: the righteous shall enter into them."

The righteous - As David was a type of Christ and the temple of heaven, so this place hath a farther prospect than David, and relates to Christ's ascending into heaven, and opening the gates of that blessed temple, both for himself and for all believers.