DirtyBird:

ridesq:

The Constitution prohibits the passing of a law that would establish a state religion.
We have enough trouble with that phrase without expanding it to an "endorsement test". I can see the Catholic Church contributing a large sum to state X in exchange for a series of large billboards saying - Catholics are OK, check 'em out.

The endorsement test is the prevailing test for determining whether an act violates the Establishment clause. It's derived from a case called Lemon v. Kurtzman, which I believe was in the 1950s.