Most of us recognize the presence of evil in our world, but according to a recent Harris Poll, the number of Americans who believe in the devil is actually dropping (from 62% in 2005 to 58% in 2013). Christianity asserts the existence of Satan (in spite of what the culture may believe), describing the devil as a limited, personal being, subordinate to a holy and good God. Satan is, according to Christianity, a personal agent of evil in our world. But is this belief in a subordinate, personal, evil being rational? Is it reasonable?