The NLRA provides that any employee who is a member of and adheres to established and traditional tenets...or teachings of a bona fide religion, body or sect which has historically held conscientious objections to joining or financially supporting labor organizations shall not be required to join or financially support any labor organization as a condition of employment....
Workers whose religious beliefs don't allow them to pay dues are entitled to alternative arrangement, allowing them to be exempt from paying dues. However, these individuals may be required to make a contribution in the same amount to a nonreligious organization or a non-labor organization, and still may be required to pay reasonable costs for grievance claims on their behalf if handled by the union.