The "Gate" of God is the Divine Word of Truth transmitted to the nations and expressed in Holy Scripture by the Patriarchs, the Prophets of God, Jesus Christ, and the Apostles, the knowledge and fulfillment of which opens to man the entrance into a state of life in righteousness.
"The Gate of Zion", "the Holy Mountain", "the City of God" symbolize the Messengers of God, the "Firstborn" of the true knowledge and fulfillment of the Will of God - Melchizedek, the Patriarchs, the Prophets, Christ, the Apostles, who by the proclamation of the Truth open to the nations the "entrance" into the knowledge of the Wisdom of the Divine Will. Through the knowledge and fulfillment of the Wisdom of God's Commandments revealed by them, man can "enter" into a state of righteousness and Eternal Life.
"The Gate of Jerusalem" is a symbol of the "Church" of God, of God's "City" - the Assembly of the Righteous, who by doing the Will of God have sanctified themselves with its spiritual "Light" to enter into a holy life filled with righteousness.
"The Gate of Jerusalem" is an image of godly people who by their righteous way of life have become a spiritual "Light" to the sinful world, and who by the preaching of the Will of God open to the nations a "Gate" for entering the world of holiness and righteousness.
Negative Meaning.
"Gates" are the various pseudo-religions, false doctrines, pernicious dogmas and ideologies propagated by false teachers, idols of society, through which the temptation to commit sin "enters" into human consciousness, creeps in.
"Gates" are a symbol of the entire world system of sinful life and evil, which plunges nations into the painful abyss of the spiritual, psychological state of "hell," i.e., lawlessness and subsequent death.
The "gate" is also all the temptations of the sinful world, through which man "enters" the state of living in iniquity, in evil.