A letter from John Newton (author of the hymn Amazing Grace) to a friend:
There is a principle of self, which disposes us to despise those who differ from us; and we are often under its influence, when we think we are only shewing a becoming zeal in the cause of God. I readily believe, that the leading points of Arminianism spring from, and are nourished by, the pride of the human heart; but I should be glad if the reverse was always true; and that to embrace what are called the Calvinistic doctrines was an infallible token of an humble mind. I think I have known some Arminians—that is, persons who, for want of clearer light, have been afraid of receiving the doctrines of free grace—who yet have given evidence that their hearts were in a degree humbled before the Lord. And I am afraid there are Calvinists, who, while they account it a proof of their humility that they are willing in words to debase the creature, and to give all the glory of salvation to the Lord, yet know not what manner of spirit they are of. Whatever it be that makes us trust in ourselves that we are comparatively wise or good, so as to treat those with contempt who do not subscribe to our doctrines, or follow our party, is a proof and fruit of a self-righteous spirit. Self-righteousness can feed upon doctrines, as well as upon works; and a man may have the heart of a Pharisee, while his head is stored with orthodox notions of the unworthiness of the creature and the riches of free grace. Yea, I would add, the best of men are not wholly free from this leaven; and therefore are too apt to be pleased with such representations as hold up our adversaries to ridicule, and by consequence flatter our own superior judgments. Controversies, for the most part, are so managed as to indulge rather than to repress this wrong disposition; and therefore, generally speaking, they are productive of little good. They provoke those whom they should convince, and puff up those whom they should edify. I hope your performance will savour of a spirit of true humility, and be a means of promoting it in others (emphasis mine).*
*Newton, J., & Richard Cecil. (1824). The works of the John Newton Volume 1 (272–273). London: Hamilton, Adams & Co.