A maxim is a conclusion upon observation of matters of fact, and is merely speculative; a "principle" carries knowledge within itself, and is prospective.
Civility also requires relearning how to disagree without being disagreeable. Surely you can question my policies without questioning my faith or, for that matter, my citizenship.
In other words, a person who is fanatic in matters of religion, and clings to certain ideas about the nature of God and the universe, becomes a person who has no faith at all.