A religious exemption will hold up under legal scrutiny better than any other basis for rejecting a mandate by an employer or government. It’s so all-encompassing under the U.S. Constitution that it has served as the basis for the Amish to be exempted from Social Security and Medicare, various religious groups to be exempted from compulsory education laws, Indian tribes to be permitted to use substances that are categorized as narcotics under the CDC for ceremonial purposes, etc.
My problem with it is that it basically accepts the premise of the mandates as valid, just with some exceptions.