Pride

Remember that pride is the worst viper that is in the heart, the greatest disturber of the soul’s peace and of sweet communion with Christ. It was the first sin committed and lies lowest in the foundation of Satan’s whole building, and is with the greatest difficulty rooted out, and is the most hidden, secret, and deceitful of all lusts, and often creeps insensibly into the midst of religion, even, sometimes, under the disguise of humility itself.

– Jonathan Edwards