Charles Devellennes looks at the the religious, social and political thought of the first four thinkers of the French Pierre Bayle, Jean Meslier, Paul-Henri Thiry d'Holbach and Denis Diderot to explicitly argue for atheism as a positive philosophy. He shows how atheism evolved considerably over the century that spans the works of these four from the possibility of the virtuous atheist in the late 17th century, to a deeply rooted materialist philosophy with radical social and political consequences by the eve of the French revolution. The metamorphosis of atheism from a purely negative phenomenon to one that became self-aware had profound consequences for establishing an ethics without God and the rise of republicanism as a political philosophy.