Science relies on the scientific method, a methodology created by man to ensure that the venture is kept in the natural world.
You can't falsify the existence of the supernatural, so you can never introduce the supernatural into any legitimate scientific theory.
Religion relies on faith.
The two ventures are merely seperate and not mutually exclusive.
I think Dr. Ken Miller, the author of "Finding Darwin's God", does the best job of laying this out.
I only have a problem with science and/or religion when one tries to transpose itself into the other.
I.e. the "intelligent design" canard.