John Newton, quoted in Credenda Agenda, Volume 5 Number 2, p. 2, from The Works of John Newton, Vol. 1, Banner of Truth, p. 272
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.