Out of curiosity, how does an organisation gets recognised as religious? Can a sufficiently determined white supremacist set up a church of all blacks are evil and start lawfully discriminating?
Out of further curiosity, would it really be so bad if that were legal? I wouldn't think a black person, or for that matter anyone who isn't a white supremacist, would want to work for that employer even if the law forced the employer to hire without discrimination.
I don't think the liquidity of the job market matters, because again, the only thing a law can feasibly do is prohibit the white supremacist employer from including those ideals in the job listing.