The religious background of John Dewey’s thought strongly affects his conception of democracy, which nevertheless explicitly claims the independence from supernatural beliefs. The ‘quasi-religious’ feature that he assigns to democratic ideals is a peculiar expression of his ‘naturalistic humanism’, which enhances imaginative capacity and scientific knowledge as basic instruments for better developing human possibilities, aside from individualism and from any form of dogmatism. The complexity of Dewey’s thought, of its sources of inspiration as well as of its most original issues, offers solid reasons for contrasting the risk of an incautious scientism and at the same time leaves room for further reflections about currents problems of democratic societies.