The Constitution requires separation of Church and State. Until we distinguish between the religious sacrament of marriage, which the State has no place regulating or even recognizing, and the social contract of marriage, which the State has every right to regulate, this issue will never be resolved.
Any religion has the right to not allow certain people to marry within its ceremonies. But that does not allow them to say that their beliefs must be imposed upon the civil marriage ceremony recognized by the state. Civil and religious marriage are entirely different institutions.