So I guess it's OK to discriminate against Christians or Jews solely on the basis of their religion, then? After all, religious observance is behavior, and certainly is not an immutable characteristic.
VR
Au contraire! The "no religious discrimination" laws - while they technically appear to deal with behavior, as opposed to immutable characteristics - are actually an extension of the "no racial discrimination" laws. The religious anti-discr. laws plug a gaping hole in the racial anti-discr. laws .... a hole big enough to drive a semi loaded with burning crosses through.
Probably the single biggest impetus for passing the religious anti-discr. laws was the existence back then - mainly in old RINO neighborhoods in the Northeast - of non-removable clauses in real estate titles that required the homeowner to never sell the property to someone "of the Hebrew faith".
Back then, there was quite a high correlation between certain religious faiths and certain races/ethnicities. (The correlations are still there, though not quite as high). So some people were making bogus claims like, "Yes, yes. I know it's against the law to discriminate against the Jewish race. But I'm not doing that. I'm discriminating only against people of the Hebrew faith!" When a racial population and a religious population have almost identical boundaries, it's easy to discriminate on the basis of race by disguising it as religious discrimination.
And the Jewish/Hebrew example is not the only one. Back then when people first saw the need for religious anti-discrim. laws, anyone who hated, say, Scandinavians, could discriminate against Lutherans and cover about 100% of their intended target group (as well as some northern Germans!) Or say, in a small southern town way back then you could declare discrimination against anyone belonging to the African Zion Methodist denomination and the Abyssinian Evangelical denomination. (Oops! Did you say those are the only two black churches in town? My, what a fantastic coincidence).