[Footnote 1: Cf. the article by Benno Erdmann cited p. 156, note.]
Intermediate between knowledge and opinion stands faith as a form of assent which is based on testimony rather than on deductions of the reason, but whose certitude is not inferior to that of knowledge, since it is a communication from God, who can neither deceive nor be deceived. Faith and the certainty thereof depend on reason, in so far as reason alone can determine whether a divine revelation has really been made and the meaning of the words in which the revelation has come down to us. In determining the boundaries of faith and reason Locke makes use of the distinction—which has become famous—between things above reason, according to reason, and contrary to reason. Our conviction that God exists is according to reason; the belief that there are more gods than one, or that a body can be in two different places at the same time, contrary to reason; the former is a truth which can be demonstrated on rational grounds, the latter an assumption incompatible with our clear and distinct ideas. In the one case revelation confirms a proposition of which we were already certain; in the other an alleged revelation is incapable of depriving our certain knowledge of its force. Above reason are those principles whose probability and truth cannot be shown by the natural use of our faculties, as that the dead shall rise again and the account of the fall of part of the angels. Among the things which are not contrary to reason belong miracles, for they contradict opinion based on the usual course of nature, it is true, but not our certain knowledge; in spite of their supernatural character they deserve willing acceptance, and receive it, when they are well attested, whereas principles contrary to reason must be unconditionally rejected as a revelation from God. Locke’s demand for the subjection of faith to rational criticism assures him an honorable place in the history of English deism. He enriched the philosophy of religion by two treatises of his own: The Reasonableness of Christianity, 1695, and three Letters on Tolerance, 1689-1692. The former transfers the center of gravity of the Christian religion from history to the doctrine of redemption; the Letters demand religious freedom, mutual tolerance among the different sects, and the separation of Church and State. Those sects alone are to receive no tolerance which themselves exercise none, and which endanger the well-being of society; together with atheists, who are incapable of taking oaths. In other respects it is the duty of the state to protect all confessions and to favor none.