Atheism has existed in various forms for well over two thousand years, but became a culturally powerful movement only in the past two centuries. Several ancient philosophers, such as Democritus and Epicurus, disputed the existence of the popular Greek and Roman gods or at least questioned their involvement in human affairs. Sextus Empiricus advocated an extreme form of skepticism that was also atheistic. The Enlightenment, an intellectual and cultural movement emerging toward the end of the eighteenth century, rejected the Bible and any other revelation and insisted on unguided human reason as the sole authority in all matters of knowledge. Enlightenment thinkers tended at first to hold to Deism, the belief that a Creator God made the universe but has no further involvement in it, but its method led quickly to atheism.
