Out of the element of participation follows the certainty of faith; out of the element of separation follows the doubt in faith. And each is essential for the nature of faith. Sometimes certainty conquers doubt, but it cannot eliminate doubt. The conquered of today may become the conqueror of tomorrow. Sometimes doubt conquers faith, but it still contains faith. Otherwise it would be indifference.
Paul TillichExistential anxiety of doubt drives the person toward the creation of certitude of systems of meaning, which are supported by tradition and authority. Neurotic anxiety builds a narrow castle of certitude which can be defended with the utmost certainty.
Paul TillichThe separation of faith and love is always a consequence of a deterioration of religion.
Paul Tillich[A] process was going on in which people were transformed into things, into pieces of reality which pure science can calculate and technical science can control. โฆ [T]he safety which is guaranteed by well-functioning mechanisms for the technical control of nature, by the refined psychological control of the person, by the rapidly increasing organizational control of society โ this safety is bought at a high price: man, for whom all this was invented as a means, becomes a means himself in the service of means.
Paul Tillich