As one who has practiced Constitutional Law, this man, unfortunately MAY be able to prevail in his suit. The key will be in the “law” that he is alleging the restaurant violated by giving discounts to those who believe in God vs. those who do not.
The governing federal statute would likely be Title II of the Civil Rights Act of 1964 (as amended), which prohibits discrimination by certain establishments such as restaurants and hotels, against protected classes of citizens based on race, religion, ethnicity, age, etc.
Using the Commerce Clause of the Constitution to extend the reach of the above statute, the US Supreme Court held that a restaurant in a southern state violated the Civil Rights Act, even though it did not accept federal funds of any kind, because it affected “interstate commerce” based on the fact that it was located near an Interstate highway.
The case is Katzenbach v. McClung, 379 U.S. 294 (1964), and is a United States Supreme Court case that held that Congress acted within its power under the Commerce Clause of the United States Constitution by forbidding racial discrimination in restaurants as this was a burden to interstate commerce. The restaurant was a family-owned bar-b-que restaurant named Ollie’s located in Alabama. It closed in 2001.
In the recent matter, the atheist will have to argue that “atheism” should be afforded the same protection as that given to minorities when it comes to accomodations in restaurants and hotels.