For pride is the beginning of sin, and he that has it shall pour out abomination: and therefore the Lord brought upon them strange calamities, and overthrew them utterly.
All Commentaries on Wisdom of Sirach 10:13 Go To Wisdom of Sirach 10
Augustine of Hippo
AD 430
"The gate of hell" means the beginning of sin because it is written, "The wages of sin is death," and to say "death" is equivalent to saying "hell." The Scripture also explains what constitutes the beginning of sin: "The beginning of every sin is pride." Therefore pride is the gate of hell. When one inquires concerning the causes that have produced heresies, one sees that they were born from pride because pride pushes people, in the end, toward heresies and schisms when they boast of their abilities and their holiness with the goal of attracting people to themselves but with the result of detaching them from Christ. But all heresies and schisms derive from these children of pride who will not overcome the catholic church, as it was precisely foretold, "The gates of hell will not prevail against it."