Three months after coming to work for the Bank of Michigan, John joins a religious group whose Sabbath is on Tuesday. Members of the religion are not to work on Tuesdays. He refuses to work on Tuesday, and is fired by the employer. When he sues for religious discrimination, the employer defends by saying: (1) John was not part of this religious group when he was hired; (2) Tuesday is not a valid Sabbath day; and (3) any group that claims Tuesday to be a Sabbath day is not valid, and the employer does not have to honor such requests. Discuss all legal issues and resolve the case.