I'd love to know what your criterion of rationality is.
Cardinal Bellarmine placemark
My idea of rationality omits the "No True Scotsman" fallacy and omits judging scientific theories by the extreme statements of polemicists.
You seem obsessed with the possibility that there might be atheists.
Well, yes, there are, and most of them are likely to be attracted to a system of knowledge that doesn't start with the assumption of an inerrant text written by God.
What you are doing is asserting that because "all" atheists are philosophical materialists, then all methodological materialists are atheists. Not just atheists, but evangelical atheists.