The most important person you've never heard of. A 19th-century German philosopher, his most important work is Die Wesen des Christentums, (The Essence of Christianity), written in 1841. In this book he lays out the basic psychological argument of atheism since that time--that God is a projection of humanity's sense of the infinite. Feuerbach argues that humans are unable to accept their own potential and so they limit themselves by projecting their ultimate potential onto an Other such as God. Instead, Feuerbach says that humanity should come to terms with its own capacity and use it, rather than wasting time worshipping a figment of its own collective imagination.

Feuerbach was a direct influence on Karl Marx and indirectly shaped the psychoanalysis and existentialism, as well as the thinking of millions of college students and would-be iconoclasts.