To believe in God is to yearn for His existence and, furthermore, it is to act as if He did exist.
Miguel de Unamuno (1864-1936) Spanish philosopher and writer [Miguel de Unamuno y Jugo]
The Tragic Sense of Life [Del Sentimiento Trágico de la Vida], ch. 5 “The Rationalist Dissolution” (1913) [tr. Flitch (1921)]
Full text.