It was in 1859—exactly a century and a half ago—that Charles Darwin published his Origin of Species, perhaps the most controversial book of the past millennium and the work that has since made Darwin the patron saint of modern atheism. According to Richard Dawkins in The Blind Watchmaker, “Darwin made it possible to be an intellectually fulfilled atheist.”
Biologist E.O. Wilson writes, “If humankind evolved by Darwinian natural selection, genetic chance and environmental necessity, not God, made the species.” Douglas Futuyma asserts in his textbook Evolutionary Biology, “By coupling undirected, purposeless variation to the blind, uncaring process of natural selection, Darwin made theological or spiritual explanations of life superfluous.” Biologist William Provine boasts that in the modern era, “evolution is the greatest engine of atheism.”
Evolution does seem to turn many Christians into unbelievers. A famous example is the distinguished Harvard biologist E.O. Wilson. Wilson writes that when he discovered evolution he felt a profound sense of intellectual liberation from his Baptist upbringing in the South. Evolution also makes some people secular evangelists for the Darwinist cause. Michael Shermer was an evangelical Christian studying at Pepperdine University when his study of evolution convinced him to give up his faith. Now the editor of Skeptic magazine, Shermer has become a kind of missionary for the atheist point of view.
So does a belief in evolution automatically lead to disbelief in God? Actually, Darwin didn't think it did. Darwin was not an "intellectually fulfilled atheist"; rather, he called himself an "agnostic." Atheists say God does not exist while agnostics say they don't know one way or the other. Moreover, Darwin didn't boast about his unbelief; rather, he approached it with marked public caution. Shocking the mores of traditional believers may be Dawkins' thing but it certainly wasn't Darwin's.
Here we must distinguish between Darwin the scientist and Darwin the unbeliever. Darwin, who was raised Anglican and even considered becoming a clergyman, did eventually relinquish his Christian faith. But he did not do so because of evolution.