The following was originally written as a letter in response to someone who felt that same-sex marriage was only about the selfish indulgence of base inclinations, while traditional marriage was modeled on the Christ-like virtues of self-sacrifice and selfless love of another.
I appreciated your thoughts about the purpose of marriage. I agree that marriage ought not to be about the fulfillment of selfish desires, but about the cultivation and practice of the virtues of altruism, serving others, and love (the "agape" kind as famously described in 1 Corinthians 13). Ideally, of course, we should be altruistic, loving and of service to all others, but being the fallible imperfect humans that we are, we can best only strive to come close to that in the context of one other person we devote our life to in marriage, and hope that the altruistic and loving tendencies that we practice within our own family might spill over a little bit into the rest of the people around us. Theologically, as you have expressed, a marriage of two fallible people should be a symbol and an imperfect reflection of the perfect love of God for his creation. God by his grace working through such marriages can inspire others and spread his grace.
The way I was raised, these ideas weren't spoken of much outside of the officiant's remarks at weddings, but I think I absorbed them more strongly by my parents' living example. I grew up with a picture in my head of what my life should be like, and there was no question that it should be centered around a marriage. Thus, at age 20, when I discovered that I was gay, the most difficult part was that my picture I'd always had, of what my life should be, seemed irreparably shattered, and there was nothing but an empty dark unknown in its place. Over time, blessed by the strong support of loving friends and family, I was able to integrate a new picture, one that preserved all of the essential values that I was raised with, but put together in a new way, in the kind of a life I would be able to live with integrity. That new picture also centered around a marriage, with all the same core values I was raised with, except that it involved two men rather than a man and a woman.
I realize that's a radical idea for you. It was a radical idea for me at one time too. But try to imagine my experience. You'll note I said I discovered that I was gay. It's certainly not something I chose. I was raised, like everybody else, thinking I was straight. I was shocked and resistant when I first realized that I wasn't straight. But I know now that being gay is profoundly who I am, and I know that I was created this way. Given that realization, there are four basic paths I could have taken:
(1) live a life of selfish hedonism
(2) marry a woman anyway, and force myself to live a "straight lifestyle"
(3) live a celibate life of monkish asceticism
(4) marry a man, and live in a completely traditional marriage aside from the gender of my spouse
Let's dismiss option 1. Hedonism would be completely untrue to who I am and the values I was raised with. I think we can agree it's not a good option.
Option number 2 is the naive solution, but we've seen too much wreckage from people who have tried that path. Marriage is challenging enough when our instinctive attractions are harnessed in the same direction as our higher goals. To lack that part of the "glue" in a marriage at the same time as attractions are pulling you in a different direction is an invitation for failure. Moreover, that choice is in conflict with the value of self-integrity (I would always being lying to myself and to others at some level), not to mention the value of putting my spouse before myself. How would that ever be fair to the woman involved, since there would always be some part of me I can't fully give her in the way she deserves, and she would be denied the opportunity to have a man who could love her in every dimension? That type of marriage is built on a rotten foundation.
Some would recommend option 3, celibacy, but that's a sad option for someone who finds themselves capable of loving commitment, to have every channel for expressing it with fidelity and integrity prohibited by legalistic moralists. I by no means wish to disparage those who find themselves called to a life of celibacy, which can be noble and rewarding. But it's frankly cruel and misguided to urge that life on those who are not called to it. I was created with a rare capacity to love another man, in the way that most men love women. None of us knows why. But wouldn't it be blasphemous to claim that God made a mistake in his creation, or that God were unable to work his grace through me as I am? I firmly believe that my capacity to love is something that can be used for good purposes, in ways that God would bless, and that it is a kind of blasphemy to squander God's gifts by letting them wither in us unused. Which leads me to option 4.
In thinking about marriage (and believe me, I have thought about it a great deal), I came to realize that there was nothing in the essential concept of it that two men couldn't undertake. Two men are as capable as a man and woman of exchanging vows of lifelong loving commitment, for richer or for poorer, in sickness and in health, and faithfully living out those vows. Two men are as capable as a man and woman of striving within their marriage to put the other first, striving to copy the example of our parents' faithful marriages, striving to be a good example for the younger generation. Two men as are capable as a man and woman of being a symbol and a vessel for God's grace.
That's the kind of marriage that George and I had in mind when we exchanged our marriage vows, and that we have been endeavoring to practice in the seven years so far that we've been living out those promises. The vows we exchanged were the same in content as yours or as any married couple, and equally solemn. Our marriage is no more a selfish indulgence in physical attractions than yours is. We're striving toward the same marriage ideal that you are, as best each of us can with the particular gifts and limitations with which God created us.