“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.”
C.S. Lewis "The Screwtape Letters" (P.S. "The Enemy", in this case, is God...). Read the book if you haven't...