What is supposed to be so harmful about gay marriage? What turns out to be the main reason Christians should want to safeguard the term 'marriage' has to do with the biblical concept of marriage, and it's something almost no one I've been reading on the topic mentions. It's no wonder that Andrew Sullivan can't find any argument for why Christians are so opposed to gay marriage. The main biblical reason never shows up on his radar.
Note: Because I had originally posted the extended entry as its own self-contained file, some of the main entry above gets repeated in what follows.
What is supposed to be so harmful about gay marriage? Will it lead to more immorality in other areas? Will it make gay people more immoral than they already are? Will it lead to immorality among children? Will it lead to a greater likelihood of the children of gay couples turning out gay? Advocates of gay marriage have trouble understanding how legalizing marriage between two people of the same sex would do any of these things. If it did any of them, then it wouldn't be a significant enough difference to justify the discriminatory practice of allowing men to marry women but not women to marry women and allowing women to marry men but not allowing men to marry men. (They also happen to think there's nothing wrong with being gay, having gay relationships, or having gay sex, which affects their evaluation of some of these supposed consequences anyway.)
I won't quibble with the details of these arguments. If there's anything to these, I don't think it's worth spending the time debating them. It shouldn't be the primary issue for Christians. What turns out to be the main reason Christians should want to safeguard the term 'marriage' has to do with the biblical concept of marriage, and it's something almost no one I've been reading on the topic mentions. It's no wonder that Andrew Sullivan can't find any argument for why Christians are so opposed to gay marriage. The main biblical reason never shows up on his radar.
The real reason is something a secularist wouldn't agree with. I'm not offering an argument for this view. What I'm giving is an explanation for what it is Christians want to protect when they say these things and why Christians see this as a good thing. The primary reason has to do with God's intent in creation. As Christians see it, God created male and female to complement each other and to demonstrate some deeper spiritual truths. When God has created humans on the sixth day, Genesis says that God created humanity, both male and female, in his image. It's possible to read that as each fully in God's image, and maybe that's one level of what's going on, but what seems to be going on (especially given what follows in the second creation account with its greater specificity of the completion of creation with both male and female in existence) is that God's image in humanity consists of both male and female somehow.
What does this amount to? One element is that a married couple reflects Christ and the church. Paul calls this a mystery in Ephesians 5, something not fully revealed in Genesis but now known through Christ. A husband is to reflect Christ's self-sacrificing servant model of leadership, giving himself for his wife as Christ gave himself for the church (see Philippians 4 for how serious a charge this is: Christ, in very nature God, gave up any right to be treated equal with God but became a man and allowed his rebellious creation to kill him). A wife is to reflect the church's willing submission to the servant leadership of Christ seeking its best interests by doing likewise with her husband. When both do this, it's an amazing picture of Christ and the church. This is part of how God created us as male and female.
Another element is the reflection of the relationship between Father and Son within the Trinity. Paul in I Corinthians 11 gives an analogy between a husband's headship of his wife, Christ's headship of every man, and God's headship of Christ. The first two follow from the Ephesians passage, but the third one really adds something. The male-female relationship is somehow modeled on the relationship between the Father and the Son. It reflects the unity and multiplicity of God, an incredible reality. The sex differences of two becoming one is written into the design of male and female. [One caveat with this point is that it doesn't put male and female on different levels. Clear statements in scripture put the Father and Son on different levels, and every statement of Christ's submission is that it's voluntary and not compelled. Christ's final submission to God at the end of all things (I Corinthians 15:27-28) reveals that he can be equal with God and yet exist in a hierarchical role. Role differences don't mean difference in level of equality before God, because God has such role distinctions within his own triune self.] The point is that marriage is the gender diversity God created coming together in one, uniting spiritually in serving God together, uniting physically in sexual knowing of each other, and (ideally) two-becoming-one genetically through producing offspring.
A third biblical element of marriage not captured in the secular notion assumed by gay marriage advocates is that it's assumed to be until death. The only exception in the scriptures is unfaithfulness, and I'm fairly confident that that's a concession to those whose spouse refuses to repent and basically abandons the family. The most common cases of unfaithfulness aren't like this, and so Hillary Clinton's commitment to her husband is the biblical way. The recent Britney Spears incident shows how far we've strayed from this idea in our popular concept of what marriage is.
So what should a Christian say about the recent political events? One thing that's clear is that a Christian shouldn't expect someone who doesn't believe all this to agree that marriage is defined in terms of these features. Since the United States government is a secular government, as it has always been, it should not be expected to build all this into the definition of marriage. (To those who think this was ever a Christian nation, I should remind you that George Washington went to his grave denying the resurrection of Christ, Thomas Jefferson edited his Bible to leave out what he didn't like, and Ben Franklin rejected Christian morality in favor of secularized ethics. It's true that Christians principles guided the founders, but that doesn't mean it was ever a Christian nation, which is an oxymoron to begin with given the biblical command for believers to be in the world but not of it.) Then why am I writing all this? I want those in support of gay rights in the area of marriage to understand what the theological principles are that so move Christians to be against allowing the term 'marriage' to apply to a same-sex couple. It need have nothing to do with thinking gay marriage will harm children. It need have nothing to do with denying gay couples health care benefits. It certainly doesn't need to stem from any desires of ill will toward gay people.
Yet it does explain the Christian's desire to retain a definition of marriage like that in the 1996 Defense of Marriage Act. This concept of marriage is important for Christian theology, and if the ordinary usage of the term 'marriage' gets any further from the Christian concept of marriage I wonder if we would have to coin a new term for that concept. It's already far enough from it that it's difficult to make any of the points I've made without this lengthy an exposition. Perhaps we need to continue in the direction of the notion of covenant marriage that a few southern states have made as legal options (basically a marriage with no legal option for no-fault divorce). But then if we start to dissociate a religious notion of marriage from the secular unions like many marriages today, why should we prevent gay couples from this secular union? It's true that Christians will still see homosexual sex and homosexual relationships as morally wrong and as violating God's plan for sex and relationships. Does that mean Christians who want to separate marriage as a holy union should oppose gay unions as a legal option even if they're secular? Just because you have theological reasons to oppose someone's actions doesn't mean you should make that behavior illegal, or we would have to advocate laws against lust, coveting in general, adultery, greed, malice, and all sorts of other things that no Christian really wants to make illegal.
At this point I'm just having a hard time figuring out why these secular unions, currently being called civil unions, should be so vehemently opposed by Christians. It doesn't serve the gospel, since it demonstrates a desire to make side issues central rather than focusing on the gospel first. It even hurts the gospel by showing that Christians like to fume about everyone else's sins rather than calling everyone to resist the sins that so tempt us all. Public repentance and acknowledgment of imperfection is far preferable to ranting about other people's particular sins, which just sounds like self-righteousness and is justly condemned by Jesus in Matthew 23. I call Christians to stop the venomous rhetoric and examine yourselves. Are you ready to criticize America for its role in furthering the sins that you yourself fall prey to? Are you ready to acknowledge that God's wrath against the United States will come just as much from the secular values the church has bought into, including those loud-mouthed critics of homosexuality? Are you ready to acknowledge that God may well intend to bring gay people in large numbers to salvation in Christ but not until Christians reach out to them in love rather than having to point out their sins all the time instead of just focusing on the general state of sin that's true of us all apart from Christ? To do that, it may take a good deal more listening, a lot more welcoming, and a lot less pursuit of legal goals that prevent gay couples from caring for those close to them and therefore offending them with issues not central to the basic gospel message.