...forgives everything more readily than an attack on truth. She knows that if a man falls, but leaves the truth unimpaired, he will find his way back again. But if he attacks the vital principle, then the sacred order of life is demolished.
--Romano Guardini, The Spirit of the Liturgy
I came to this realization long ago and it became one of my fundamental principles, in a sense preceding the doctrines of faith. But it seems a common error in our time to be unable to distinguish between the failure to live up to a principle and the denial of the principle.