closed system or closed mind?

If the study of physics shows that nature is a closed system and it is, strictly speaking, a scientific fact that miracles and freedom are impossible, then it would seem that a theist could not do physics well. But what about the fact that there are and have been successful physicists who believe in God and freedom?  Apparently theism did not  keep George Lemaitre from discovering the big bang!  If, on the other hand, one's ability to do physics is not adversely affected by theism etc., then the exclusion of miracles and freedom is not so much a scientific fact as as a philosophical inference--or perhaps an act of faith.