From my old stomping grounds of South Florida comes this interesting story:
This type of thing happens more than we would think. The problem here is that they let this employee have Saturdays off for two years and then changed the rule. The nursing home will be unlikely to prevail on a “business necessity” defense. There is an exemption under Title VII for employment in religion-affiliated organizations, but only for positions that are directly connected to the religion: priest, rabbi, etc.