(on the 1st Amendment seemingly making Christianity equal to all other religions)

The real object of the Amendment was not to countenance, much less to advance Mohammedanism, or Judaism, or infidelity by prostrating Christianity, but to exclude all rivalry among Christian sects and to prevent any national ecclesiastical establishment which should give a heirarchy the exclusive patronage of the national government. It thus cut off the means of religious persecution (the vice and pest of former ages).

Furthermore...

At the time of the adoption of the Constitution, the general, if not universal sentiment in America was that Christianity ought to receive encouragement from the State. An attempt to level all religions and to make it a matter of State policy to hold all in utter indifference would have created universal disapprobation, if not universal indignation.