One's religious convictions and expressions of same ARE protected by the 1st amendment and no law can alter that(with the caveat that no one has the right to take a life over it. All our rights are derived from the right to life-James Madison) Your non argument is misleading and irrelevant. 
Read Chief Justices' Commentaries on the Constitution. The 1st amendment was not to prostrate Christianity (98% of the country at the Founding was Christian) to atheism, Catholicism, Mohammedism, or Armenianism but to prevent strife among Christian denominations and persecution of same by government endorsement of any particular denomination.