In arguments about gay marriage you sometimes hear suggestions that we should have a strictly civil version of marriage (or union) for the public realm that applies to gay and straight people alike, while leaving “sacred” marriage to religious bodies. This may or may not be a good idea, but what I wonder is whether there’s good reason for thinking of marriage as “sacred” in the first place.
In the Lutheran tradition, at any rate, you could argue that marriage is part of the “kingdom of the left”–God’s ordering of civil institutions for the sake of human well-being in this world. Lutherans don’t see marriage as a sacrament, and it’s debatable whether it should be seen even as especially sacred, at least any more than any other legitimate calling. The justification for marriage, like any other institution belonging to the left-handed kingdom, is that it conduces to human well-being. It’s not a matter of salvation, which belongs exclusively to God’s right-handed rule: the proclamation of free grace, forgiveness, and salvation in Christ.
What this line of thinking might lead to is not the abandonment of civil marriage, but the abandonment of religious marriage! This isn’t necessarily to say that churches shouldn’t continue to bless marriages; churches properly bless a whole host of things. (I once heard a gay Christian point out that churches bless everything from pets to apartments, so why couldn’t they bless his relationship? Good question!) What it does mean is that the church, in blessing such a union, isn’t creating some special “religious” relationship. Rather, it’s recognizing that union as a place or station in life where people can serve God, grow in virtue, be restrained from sin, learn to love each other, and contribute to the common good. But there wouldn’t be any reason to talk about “religious” marriage as having some sort existence distinct from or parallel to “secular” marriage.
Obviously, this position won’t be acceptable to Catholics and others who regard marriage as a sacrament. But in the case of Protestants, for whom the church’s raison d’etre is the proclamation of the Gospel in Word and Sacrament, it’s far from clear to me what authority we have for investing various human institutions with “religious” or quasi-sacramental significance.
I’m not at all wedded to this position (you’ll pardon the expression), but it’s worth thinking about.