There is nothing so hardening as unbelief; and one great reason for this is, that there is nothing so deceitful. It does not look a great sin; nay, sometimes not like sin at all, but like modesty and humility. It pretends to be jealous for God, to be conscious of personal unworthiness, to be unfit to venture on a hope of acceptance. Thus, it deceives… It actually hides itself, lessens its own wickedness, veils its hatefulness under the name of humility. In all these ways, it contrives to destroy faith, to cherish itself, and so to harden the heart.