In those who rest on their unshakable faith, pharisaism and fanaticism are the unmistakable symptoms of doubt which has been repressed. Doubt is not overcome by repression but by courage. Courage does not deny that there is doubt, but it takes the doubt into itself as an expression of its own finitude and affirms the content of an ultimate concern. Courage does not need the safety of an unquestionable conviction. It includes the risk without which no creative life is possible.
Paul TillichWhy does philosophy use concepts and why does faith use symbols if both try to express the same ultimate? The answer, of course, is that the relation to the ultimate is not the same in each case. The philosophical relation is in principle a detached description of the basic structure in which the ultimate manifests itself. The relation of faith is in principle an involved expression of concern about the meaning of the ultimate for the faithful.
Paul TillichThe courage to be is rooted in the God who appears when God has disappeared in the anxiety of doubt.
Paul Tillich