Screwtape offers ways to cleverly exploit the Patient’s dry spell:

But there is an even better way of exploiting the trough; I mean through the patient’s own thoughts about it. As always, the first step is to keep knowledge out of his mind. Do not let him suspect the law of undulation. Let him assume that the first ardours of his conversion might have been expected to last, and ought to have lasted, forever, and that his present dryness is an equally permanent condition. Having once got this misconception well fixed in his head, you may then proceed in various ways. It all depends on whether your man is of the desponding type who can be tempted to despair, or of the wishful-thinking type who can be assured that all is well. The former type is getting rare among the humans. If your patient should happen to belong to it, everything is easy. You have only got to keep him out of the way of experienced Christians (an easy task nowadays), to direct his attention to the appropriate passages in scripture, and then to set him to work on the desperate design of recovering his old feelings by sheer will-power, and the game is ours. If he is of the more hopeful type your job is to make him acquiesce in the present low temperature of his spirit and gradually become content with it, persuading himself that it is not so low after all. In a week or two you will be making him doubt whether the first days of his Christianity were not, perhaps, a little excessive. Talk to him about ‘moderation in all things’. If you can once get him to the point of thinking that ‘religion is all very well up to a point’, you can feel quite happy about his soul. A moderated religion is as good for us as no religion at all—and more amusing.

From The Screwtape Letters
Compiled in A Year with C.S. Lewis

The Screwtape Letters. Copyright © 1942, C. S. Lewis Pte. Ltd. Copyright restored © 1996 C. S. Lewis Pte. Ltd. All rights reserved. Used with permission of HarperCollins Publishers. A Year With C.S. Lewis: Daily Readings from His Classic Works. Copyright © 2003 by C. S. Lewis Pte. Ltd. All rights reserved. Used with permission of HarperCollins Publishers.