Silence in the face of evil is itself evil; God will not hold us guiltless. Not to speak is to speak. Not to act is to act.

Dietrich Bonhoeffer (1906-1945) German Lutheran pastor, theologian, martyr

(Spurious)

Frequently attributed to Bonhoeffer, but not found in his works. The origins of its attribution are discussed here, and the phrasing seems to more or less originate with Robert K. Hudnut, A Sensitive Man and the Christ (1971).