As a straight person of faith as well as a constitutional and citizenship scholar, I find the use of religion as the basis for deciding the recent Supreme Court's marriage case as a failure to fully understand our constitution. As part of our governmental system as well as a recognition of the importance of accepting diverse religious views, the U.S. Constitution, through the establishment clause, specifically requires that our laws be separate from our religious views, or at least that the government not be deemed to support one particular religion's views. Hence the term: the separation of church and state.
Ironically, in the context of marriage, a social status that comes with a host of preferential rights and privileges (just look to our family laws, health laws, tax laws, and our laws relating to trusts and estates, just to name a few), we have inverted and arguably perverted the establishment clause, and by extension our constitution. We have in essence conflated, or shall I say mixed, our religious views with the bundle of rights that come with marriage to deny certain individuals the preferred rights (at least when compared to single persons) that come with marriage. We are thus not only not separating religion and law, we are using religion as the basis to deny rights, i.e., the power and privileges of the law, to those that would otherwise be eligible to the preferred rights associated with citizenship. Thus, irrespective of one's religious views, I hope most learned people can appreciate that if under the establishment clause we are to separate our laws and our religious views, we should not use religion or a religious concept as the legal basis to deny rights. That is exactly what the establishment clause was intending to avoid.
If you must, and are unwaveringly tied to labels, I would agree that perhaps no one in our society should be entitled to a legal label called "being married," if in fact the term is religious only. It is simply not a appropriate under our constitutional structure to advocate for some citizens to have a form of inferior rights than other citizens. Thus, the legal label and the bundle of rights that comes with marriage should be eligible to all people, irrespective of religious views, political, or social views.