A business couldn’t legally ban Christians, but the Civil Rights Act of 1964 is clearly unconstitutional. The government can’t amend the constitution via law, and those class protections restrain government, not citizens. The 14th Amendment extended those protections to states (state governments), but again, nowhere in the constitution does it say I can’t discriminate on the basis of sex, race, or religion so long as I’m not acting in government capacity, like an official.
If I’m wrong, please point me to the area of the constitution that limits my right to associate or not associate with whoever I want.
The U.S. Supreme Court upheld the constitutionality of the Public Accommodations Act of 1964 (part of the Civil Rights Act of 1964) as a valid exercise of Congress's power to regulate interstate commerce, on the theory that racial discrimination in hotels and restaurants in the south limited the ability of blacks to travel to those states.