Same answer as the other anon asking the same question:

You don't need to "prove" your religious beliefs. Just state them.

"Congress shall make no law respecting an establishment of religion, nor prohibit the free exercise thereof;" -- 1st Amendment, US Constitution

This applies to the states, as well, via the 14th Amendment, and probably via your state's constitution.

The government cannot determine what is or is not a religious belief. What makes a private party (business) think they have any legal authority to do it?

Stand your ground, and DEFEND YOUR RIGHTS.

DO NOT ASK PERMISSION.

Same answer as the other anon asking the same question:

You don't need to "prove" your religious beliefs. Just state them.

"Congress shall make no law respecting an establishment of religion, or the free exercise thereof;" -- 1st Amendment, US Constitution

This applies to the states, as well, via the 14th Amendment, and probably via your state's constitution.

The government cannot determine what is or is not a religious belief. What makes a private party (business) think they have any legal authority to do it?

Stand your ground, and DEFEND YOUR RIGHTS.

DO NOT ASK PERMISSION.