Galatians 6:9

And let us not grow weary in well-doing, for in due season we shall reap, if we do not lose heart.

In The Screwtape Letters, C. S. Lewis’ senior demon, Screwtape, explains to a junior demon, Wormwood, why God sends us “dry times”:

He will set them off with communications of His presence which, though faint, seem great to them, with emotional sweetness, and easy conquest over temptation. But He never allows this state of affairs to last long. Sooner or later He withdraws, if not in fact, at least from their conscious experience, all those supports and incentives. He leaves the creature to stand up on its own legs–to carry out from the will alone duties which have lost all relish. It is during such periods, much more than during the peak periods, that it is growing into the sort of creature He wants it to be. Hence the prayers offered in the state of dryness are those which please Him best. We can drag our patients along by continual temptation, because we design them for the table, and the more their will is interfered with the better. He cannot “tempt” them to virtue as we do to vice. He wants them to learn to walk and must therefore take away His hand; and if only the will to walk is really there, He is pleased even with their stumbles. Do not be deceived, Wormwood. Our cause is never more in danger than when a human, no longer desiring, but still intending to do our Enemy’s will, looks round upon a universe from which every trace of Him seems to have vanished, and asks why he has been forsaken, and still obeys.