The board can remove the person, not because he is a muslim, but simply because he is a trespasser. That is, the board doesn't need a reason to remove someone from the church. The board can remove anyone at will.
If it were a restaurant, theater, hotel, auditorium, airport, etc., it would violate the person's civil rights. But, a church, as a place of worship for a particular sect, is protected -- it is not a public accommodation subject to the civil rights act.
Note: I'm not taking a political position, here. Federal law does not include churches in the definition of "public accommodations." 42 U.S.C. 12187.
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