In his book Darwin’s Dangerous Idea, Dennett contends that Darwin’s theories are a kind of “universal acid” that “eats through just about every traditional concept, and leaves in its wake a revolutionized worldview” about the nature of man and the universe. Specifically, Dennett and others interpret Darwinism to mean that all life can be understood entirely in natural and material terms. Man is nothing more than matter in motion. The soul? A product of fantasy. The afterlife? A myth. Human purpose? An illusion.

Leading biologists spell out some of the implications. As Darwin has shown how life is “the result of a natural process,” Francisco Ayala writes, we are “without any need to resort to a Creator.”” In an essay on evolution and its implications, William Provine writes, “Modern science directly implies that there are no inherent moral or ethical laws, no absolute guiding principles for human society…. We must conclude that when we die, we die, and that is the end of us.”

Many scientific atheists portray man as simply a carbon-based machine, a purely material object whose belief in immaterial things is a kind of epiphenomenon or illusion. Biologist Francis Crick, who helped to discover the structure of DNA, writes that all biology is reducible to the laws of physics and chemistry. Life is the product of the same mechanical operations as the inanimate matter in nature. Consciousness is “no more than the behavior of a vast assembly of nerve cells and their associated molecules.” Biologist E. 0. Wilson writes that the hidden operations of our mental activity give us “the illusion of free will.”

For centuries, cognitive scientist Steven Pinker points out, religion has taught men to believe in an immortal soul that inhabits our bodies, a kind of “ghost in the machine.” But modern science has, in Pinker’s view, destroyed that belief. “The mind is the physiological activity of the brain” and “the brain, like other organs, is shaped by the genes” and those have been “shaped by natural selection and other evolutionary processes.” Therefore the mind is nothing more than “an entity in the physical world, part of a causal chain of physical events:’ When the brain decays through aging or disease, the mind disappears. As for the soul? Pinker ringingly declares that “the ghost in the machine has been exorcised.”

This scientific atheism has its roots in the Enlightenment. Leading thinkers of the Enlightenment, like Voltaire, were anti-clerical and anti-religious rather than atheist. Denis Diderot and Baron d’Holbach did, however, introduce a full-fledged atheism to the educated population of Europe. These thinkers viewed science as a privileged form of knowledge based on reason and criticism and testing, and viewed religious doctrine as a form of ignorance rooted in myth, coercion, and fear. As Voltaire put it, “There are no sects in geometry.” That’s because there are methods of verification that enable all scientifically minded people to agree on the facts.

Modern doctrines of materialism and naturalism, which hold that matter is the only reality and that there are no supernatural influences in nature, have their foundation in the atheistic wing of the Enlightenment. Modern atheists have employed these ideas to formulate their influential theories. Marx, for instance, portrayed religion as the “opiate of the masses,” a drug that dulls the mind, preventing it from comprehending the scientific forces acting upon history. Freud, in his 1927 book The Future of an Illusion, termed belief in God a comforting illusion invented by human beings to avoid facing the reality of death. When Richard Dawkins states in The God Delusion that he holds his beliefs “not because of reading a holy book but because I have studied the evidence.” he is placing himself squarely in this tradition of the skeptical Enlightenment.