Sex, especially homosexuality, is a big deal because how one comes down on those related questions has a lot to do with how you view the authority of Scripture and Tradition. There's a reason why the churches today are breaking apart over homosexuality, and it has to do with the plain fact that there can be no compromise on this issue, as it goes to the heart of how believers understand ourselves, our relationship to God, and to the nature of truth. This stuff matters. It matters a lot.
Linker deals with Dreher's retreat to Biblical literalism (in sum: why do Christians retreat to the Bible only when it suits their argument?) but Dreher misses something else. The struggle for gay rights is frequently paralleled to the African-American struggle for civil rights, for obvious reasons. But the civil rights movement, starting before even the Civil War, also had the effect of dividing American churches against themselves. Just like today, church-goers of all denominations in the 19th and 20th centuries believed that there could be "no compromise" on the issue of slavery and civil rights. Southern church-goers frequently cited to the Bible as a defense of slavery. But how many arguments between denominations do we hear about the correctness of civil rights, or slavery now? Not only was there eventually compromise on these issues, the anti-slavery and pro-civil rights forces won. There is simply no argument about these issues in mainstream churches anymore, and that despite the fact that at one point in time, a substantial number of Christians in America believed that the Bible offered literal support for racist slavery.
Rod Dreher is right that the issue of homosexuality divides churches because of intense feelings on both sides. But Dreher's citing to the divison of churches over the issue of homosexuality is not the compelling evidence of the importance of the issue that he thinks it is. And he's wrong to say that no compromise is possible. In fact, it's quite easy to predict that the gay rights movement will track the civil rights movement in this manner too. It's just not that likely that, one hundred years from now, Christians of all denominations will be arguing over what the Bible thinks of homosexuality. And that's what I think people like Dreher fear the most.