Bayle argues that in any Christian theology hides a form of dualism. Manichaeism, therefore, have not been vanquished, although its historical forms has been completely discredited. This essay analyzes Leibniz’s response to Bayle’s provocation: while rejecting Manichaeism, the philosopher of Hanover does not hesitate to recognize a form of dualism within God himself. After two and a half centuries, Karl Barth found himself wrestling with the same possibility. Evil for Barth is alien power of Nothingness that arises mysteriously from what God does not will in the act of creation. Despite his harsh criticism of Leibniz, Barth does not seem to be able to distance himself from the underlying structure of theodicy.

Keywords: Pierre Bayle; Gottfried Wilhelm von Leibniz; Karl Barth; Theodicy; Manichaeism.