Guilt
Remember the story in the Imitation [The Imitation of Christ by Thomas à Kempis], how the Christ on the crucifix suddenly spoke to the monk who was so anxious about his salvation and said “If you knew all was well, what would you, to-day, do, or stop doing?” When you have found the answer, do it or stop doing it. You see, one must always get back to the practical and definite. What the devil loves it that vague cloud of unspecified guilt feeling or unspecified virtue by which he lures us into despair or presumption. “Details, please!” is the answer.
I wonder whether you are on the right track expecting “stable sentiments” and “successful adjustment to life.” This is the language of modern psychology rather than of religion or even of common experience, and I sometimes think that when the psychologists speak of adjustment to life they really mean perfect happiness and unbroken good fortune! Not to get—or, worse still, to be—what one wants is not a disease that can be cured, but the normal condition of man. To feel guilty, when one is guilty, and to realize, not without pain, one’s moral and intellectual inadequacy is not a disease, but commonsense. To find that one’s emotions do not “come to heel” and line up as stable sentiments in perfect conformity with one’s convictions is simply the facts of being a fallen, and still imperfectly redeemed, man. We may be thankful if, by continual prayer and self-discipline, we can, over the years, make some approach to that stability. After all, St. Paul, who was a good deal further along the road than you and I, could still write Romans, Chapter 7, verses 21-23.
The Collected Letters of C.S. Lewis, Volume III