A convicting quote from Jonathan Edwards, lightly modernized here by Ray Ortlund:
Spiritual pride is the main door by which the devil comes into the hearts of those who are zealous for the advancement of Christianity.
It is the chief inlet of smoke from the bottomless pit, to darken the mind and mislead the judgment.
It is the main source of all the mischief the devil introduces, to clog and hinder a work of God.
Spiritual pride tends to speak of other persons’ sins with bitterness or with laughter and levity and an air of contempt. But pure Christian humility rather tends either to be silent about these problems or to speak of them with grief and pity.
Spiritual pride is very apt to suspect others, but a humble Christian is most guarded about himself.
He is as suspicious of nothing in the world as he is of his own heart.
The proud person is apt to find fault with other believers, that they are low in grace, and to be much in observing how cold and dead they are and to be quick to note their deficiencies.
But the humble Christian has so much to do at home and sees so much evil in his own heart and is so concerned about it that he is not apt to be very busy with other hearts.
He is apt to esteem others better than himself.
—Jonathan Edwards, “Thoughts on the Revival,” Works (Edinburgh, 1979), I:398-400.