OK, as helpful as they may sound, the cold\heat and light\darkness analogies fall too short. Evil is not simply a passive absence of its opposite. It is an active, willful deviation from that which is good. God exists, evil exists, and no matter how you slice it, God created a universe in which there would be evil, and since He is Sovereign, He ordained that it be so, for the display of His Glory. The Fall of man and the plan of redemption were not a "Plan B." Jesus is "the Lamb slain from the foundation of the world."