Perelandra by C.S. Lewis

Pitted against the most destructive of human weaknesses, temptation, the great man must battle evil on a new planet -- Perelandra -- when it is invaded by a dark force. Will Perelandra succumb to this malevolent being, who strives to create a new world order and who must destroy an old and beautiful civilization to do so? Or will it throw off the yoke of corruption and achieve a spiritual perfection as yet unknown to man? The outcome of Dr. Ransom's mighty struggle alone will determine the fate of this peace-loving planet.