Congress shall make no law respecting an establishment of religion, or prohibiting the free exercise thereof; or abridging the freedom of speech, or of the press; or the right of the people peaceably to assemble, and to petition the Government for a redress of grievances.
The problem being that if the Federal Government is providing (i.e., supporting from federal revenues) facilities for religious purposes, it necessarily implies endorsement of some religions (those that sign up first to use a limited facility, for example) to the exclusion of others (those that sign up last or have too few members to warrant use of the facility.) It's a game the founders clearly wanted government not to play - (which is why it is the first clause of the first amendment) and if you read the Supreme Court decisions at al, you'll realize that a violation of the Establishment Clause is the one are in which a taxpayer has general standing to challenge an act of the government (based on status as a taxpayer alone).
Nice try but its wrong.
Its not the first ammendment because its important: its first because 2 others were not approved.[ http://www.constitution.org/billofr_.htm ]
Also: there has never been any problem until very recently with religious expression in this country. Now anything with the whiff of religion becomes a cause celebre’ for people bent on denying it. Your reading of the clause, while in line with the wrong-headed court rulings is simply twisting the pretzel into contortions it should not have.