In the sphere of human relations, faith is an indispensable quality of any significant friendship or love. "Having faith" in another person means to be certain of the reliability and unchangeability of his fundamental attitudes, of the core of his personality, of his love. By this I do not mean that a person may not change his opinions, but that his basic motivations remain the same; that, for instance, his respect for life and human dignity is part of himself, not subject to change.
Erich Fromm, The Art of Loving
philosophy, psychology