Every writing career starts as a personal quest for sainthood, for self-betterment. Sooner or later, and as a rule quite soon, a man discovers that his pen accomplishes a lot more than his soul.
Good writers define reality; bad ones merely restate it. A good writer turns fact into truth; a bad writer will, more often than not, accomplish the opposite.
I have a great deal of religious symbolism in my stories because I have a very deep sense of religion and also I have religious training. And I suppose you don't say, "I'm going to have the flowering judas tree stand for betrayal, but of course it does.