Amendment I targets one government entity, and one entity only - Congress. And the last time I checked, Congress did not pass a law mandating that Arkansas State football players wear crosses on their helmets. So anyone saying that this violates the Constitution can go pound sand as far as I'm concerned. And Arkansas State ought to put those crosses back on just to see how far the government is willing to go to enforce the fascist state.
Then of course there is the Arkansas State Constitution to consider. Here's how it begins:
We, the People of the State of Arkansas, grateful to Almighty God for the privilege of choosing our own form of government; for our civil and religious liberty; and desiring to perpetuate its blessings, and secure the same to our selves and posterity; do ordain and establish this Constitution.