I have only dabbled a tiny bit in C.S. Lewis, never gravitating to him as many other serious believers do — and this lack of acquaintance may be to my detriment. So, I recently pulled off my shelves The Joyful Christian, a volume in which are compiled many writings on various topics. I’ve sampled a couple dozen of these and would like to offer this section that I found as honest as it is helpful:
The New Testament contains embarrassing promises that what we pray for with faith we shall receive. Mark 11:24 is the most staggering. Whatever we ask for, believing that we’ll get it, we’ll get. No question, it seems, of confining it to spiritual gifts; whatever we ask for. . . . No question of getting either it or else something that is really far better for you, you’ll get precisely it. . . .
How is this astonishing promise to be reconciled (a) with the observed facts? and (b) with the prayer in Gethsemane, and (as a result of that prayer) the universally accepted view that we should ask everything with a reservation (“if it be Thy will”)?
As regards (a), no evasion is possible. Every war, every famine or plague, almost every deathbed, is the monument to a petition that was not granted. . . .
But (b), though much less often mentioned, is surely an equal difficulty. How is it possible at one and the same moment to have a perfect faith—an untroubled or unhesitating faith as St. James says (1:6)—that you will get what you ask and yet also prepare yourself submissively in advance for possible refusal? If you envisage a refusal as possible, how can you have simultaneously a perfect confidence that what you ask will not be refused? If you have that confidence, how can you take refusal into account at all? . . .
It seems to me we must conclude that such promises about prayer with faith refer to a degree or kind of faith which most believers never experience. A far inferior degree is, I hope, acceptable to God. Even the kind that says, “Help Thou my unbelief” may make way for a miracle. Again, the absence of such faith as insures the granting of the prayer is not even necessarily a sin; for Our Lord had no such assurance when he prayed in Gethsemane.
– C.S. Lewis