Can private clubs and religious organizations legally discriminate?
That depends. When dealing with private individuals, the Federal civil rights statutes only reach as far as public accommodations. Thus, while it is unlawful to discriminate on the basis of race or national origin in hotels, restaurants, theaters, public transportation and public parks, the Federal civil rights laws do not make it unlawful for bona fide private clubs and religious organizations to discriminate on whatever basis they choose.
Many states have enacted laws that go well beyond the protections afforded by the Federal laws, both in terms of their scope of prohibited conduct and their application to what might be regarded by some as private clubs or organizations. For example, in March 1998, a divided New Jersey Appeals Court decided that New Jersey's Civil Rights Law prohibited the Boy Scouts from discriminating against a scoutmaster because of gender preferences, while in a similar case across the country, the California Supreme Court held that California Civil Rights Law did not prohibit the Boy Scouts from denying membership to persons who are gay or do not believe in God.
Some cities, including Chicago, New York and San Francisco, also have local Civil Rights Laws that are far broader than the Federal law. For example, New York City defines private clubs that derive certain levels of income from business as places of public accommodation for purposes of its Civil Rights Laws. San Francisco requires employers who do business with the city to offer their employees health insurance for non-marital "partners".