The Dangers of Spiritual Pride

"The first and the worst cause of errors, that prevail in such a state of things, is spiritual pride. This is the main door by which the devil comes into the hearts of those who are zealous for the advancement of religion. It is the chief inlet of smoke from the bottomless pit, to darken the mind and mislead the judgment. This is the main handle by which the devil has hold of religious persons, and the chief source of all the mischief that he introduces, to clog and hinder a work of God.—This cause of error is the main spring, or at least the main support, of all the rest. Till this disease is cured, medicines are in vain applied to heal other diseases. It is by this that the mind defends itself in other errors, and guards itself against light, by which it might be corrected and reclaimed. The spiritually proud man is full of light already, he does not need instruction, and is ready to despise the offer of it. But, if this disease be healed, other things are easily rectified. The humble person is like a little child, he easily receives instruction . . .
Pride is much more difficult to be discerned than any other corruption, because its nature very much consists in a person’s having too high a thought of himself. No wonder that he who has too high a thought of himself, does not know it; for he necessarily thinks that the opinion he has of himself has just grounds, and therefore is not too high . . .
The heart is deceitful and unsearchable in nothing so much as in this matter; and there is no sin in the world, that men are so confident in. The very nature of it is to work self-confidence, and drive away [humility]."
Jonathan Edwards, The Works of Jonathan Edwards, vol. 1 (Banner of Truth Trust, 1974), 398–399.