To know the true nature of pride, we should first note that it is a spiritual sin, in itself less shameful and less debasing, but more grievous, says St. Thomas,(1) than the sins of the flesh, because it turns us more away from God. The sins of the flesh could not be in the demon who was irremediably lost through pride. Scripture on several occasions says that "pride is the beginning of all sin," (2) because it does away with the humble submission and obedience of the creature to God. The first sin of the first man was a sin of pride,(3) the desire of the knowledge of good and evil,(4) that he might be his own guide and not have to obey. In the opinion of St. Thomas,(5) pride is more than a capital sin; it is the source of the capital sins, and particularly of vainglory, which is one of its first effects.
Some are deceived, at least practically, about the true nature of pride, and as a result, without wishing to do so, may commend false humility, which is a form of hidden pride more dangerous than that which displays itself and makes itself ridiculous. - Garrigou-Lagrange
What is more ridiculous than the burlesque theatrics of a gay pride parade?