Tim Keller, writing in his new book King’s Cross (on the Gospel of Mark), looks at how saying “I’m unworthy” can sometimes function not as a plea for deliverance but as a form of pride:
There are two ways to fail to let Jesus be your Savior.
One is by being too proud, having a superiority complex—not to accepted his challenge.
But the other is through an inferiority complex—being so self-absorbed that you say, “I’m just so awful that God can’t love me.” That is, not to accept his offer.
Keller goes on to quote from John Newton’s letter to a very depressed correspondent:
You say you feel overwhelmed with guilt and a sense of unworthiness.
Well, you cannot be too aware of the inward and inbred evils you complain of, but you may be (indeed you are) improperly controlled and affected by them.
You say it is hard to understand how a holy God could accept such an awful person as yourself.
You, then, not only express a low opinion of yourself (which is right!) but also too low an opinion of the person, work, and promises of the Redeemer, which is wrong. . .
You complain about sin, but when we examine your complaints, they are so full of self-righteousness, unbelief, pride, and impatience that they are little better than the worst evils you complain of!
—Works of John Newton, vol. 6, p. 185.