I would like to start with a personal memory. When I was young I would sometimes go to church with my maternal grandma. She was a devout Episcopalian. My sister and I would color in the pews and play with the kneeling bench during the service. As I got older my grandma would invite me up to receive a blessing. I didn't understand why I couldn't have a cracker and drink out of the cup like she did. I knew that it wasn't that I was a child as there were children younger than me who got crackers. Eventually as I grew older, and understood better the sacraments, I started understanding what was going on. I was not part of the community in that sense because I had not been baptized. I came to respect this position though my perspectives lean clearly on the side of anabaptism.
Baptism isn't really the sacrament that I am here to discuss. Communion isn't really the focus of this post either. Rather, I'm here to discuss the sacrament of marriage. Different churches have different standards, beliefs, and practices concerning the sacraments mentioned above. I'm okay with that. During my time at Pacific Lutheran University I really got an opportunity to explore the power of ecumenical fellowship. Churches are a safe place to come together with people of the same mind. Even so, the details of what distinguishes one christian from another in issues of faith does not change our common status as children of God.
In my grandma's church, I could have argued discrimination. I was excluded from the community sacrament due to my status as an unbaptized person. I didn't though and I think it would be unhelpful to think that way. It wasn't my church. It wasn't where I found like-minded people. I was an ecumenical visitor to their community. This discrimination was fine and justified to uphold the principles of faith within this church. The fact that I couldn't enter into communion there also did not impact my ability to receive communion at other churches. (And it certainly didn't prevent me from eating crackers and drinking grape juice either at home or in public spaces.)
This is very much how I feel about the sacrament of marriage. Marriage can have a personal, a civil, and a religious context. Religious rights need to be maintained. The sacrament of marriage is just that, a sacrament. It is sacred and its requirements vary from faith community to faith community. Churches should be able to maintain the right to choose whether or not to perform the ceremony, just like my grandma's church had the right to deny me access to communion before baptism. It is a matter of conscience, faith, and community.
Just like my grandma's church had no power to legislate the conditions of communion in other faith communities, so too the conservative faith communities that hold different biological sex to be a requirement for entering into the sacrament of marriage can't extend that requirement to other communities for whom same-sex marriage does not violate their faith and conscience. Same sex marriage does not violate the sanctity of marriage so long as churches maintain the right to perform or not perform marriage ceremonies according to their faith.
One thread thrown around concerning marriage sanctity from the left is about how a committed relationship is more sacred than the celebrity marriages that end in a matter of days or weeks. The right has claimed that the objective definition of marriage is one man and one woman and anything else is essentially something else. What I hear in these arguments is that there are real marriages and there are fake marriages. In my opinion it is not up to you to decide who has a real marriage and who has a fake marriage. It is none of your business. Discrediting other people's marriages doesn't actually make yours any more special. The fact that others have marriages that don't fit your marriage box doesn't mean that theirs is less special.
Not convinced? That's fine. Let's start from the presumption that there are in fact real marriages and fake marriages. The meaning attached is one of community and personal choice. A cracker and grape juice can be just that, or it can be a representation of the body and blood of Christ. If you believe in transubstantiation, it can be the actual body and blood of Christ. Each of these interpretations does not preclude the other interpretations. Perhaps you feel like marriage is more important than the distinctions here but let me remind you that these were issues over which christians of long ago would fight and die. We are peaceful and tolerant about it now but there was a time where people thought that a change in this sacrament would be the downfall of society.
Finally it is important to recognize that not all marriages are sacred by the technical religious definition. Many people get married without the sacrament being performed by a priest. People can get married by going down to the courthouse and filling out the paperwork. When people do this it is not a threat to the sanctity of your marriage because your marriage means something different to you. It is the same thing with same sex marriage. You can believe it is different if you want, because your church has a different definition but just like you wouldn't prevent people from eating crackers and drinking grape juice in a non-religious context, it makes no sense to prevent consenting adults from building a life together in a non-religious context or in a religious context that is separate from yours.