Whatever in our present success mere Fashion has given us, mere Fashion will presently withdraw. The real conversions will remain: but nothing else will. In that sense we may be on the brink of a real and permanent Christian revival: but it will work slowly and obscurely and in small groups. The present sunshine (if I may so call it) is certainly temporary. The grain must be got into the barns before the wet weather comes.
This mutability is the fate of all movements, fashions, intellectual climates and the like. But a Christian movement is always up against something sterner than the mere fickleness of taste....The enemy has not yet thought it worth while to fling his whole weight against us. But he soon will....Neither our armour nor our enemies' is yet engaged. Combatants always tend to imagine that the war is further on that it really is.

C.S. Lewis. "The Decline of Religion" in GOD IN THE DOCK.