The most emphatic single sentence in the entire constitution of the United States is in Article VI:
" . . . no religious Test shall ever be required as a Qualification to any Office or public Trust under the United States . . ."
The plain language couldn't be more emphatic: " ... no ... ever ... any ... " One could argue about whether a military post is an "office" or a "public Trust" but my guess is that it easily fits the bill (notary public was the big Supreme Court case on the matter).
This article available online at:
http://www.theatlantic.com/international/archive/2009/11/muslim-soldiers-and-the-constitution/30450/
