For some secular liberals, the Constitution isn't the only "living, breathing document." The Bible is, too.

For evidence, look no further than Frank Bruni's latest New York Times column, which argues that "homosexuality and Christianity don't have to be in conflict in any church anywhere." According to this line of argument, Christians ought to engage in "a conversation about freeing religions and religious people from prejudices that they needn't cling to and can indeed jettison, much as they've jettisoned other aspects of their faith's history, rightly bowing to the enlightenments of modernity."

Now, Bruni's core argument is not without merit. Things change, and that includes religions. There are various interpretations of the Christian faith, and attitudes on any number of issues have shifted quite a lot over time.

But here's the problem: You don't have to go much further than Bruni has to argue not only that believers should bow to "the enlightenments of modernity," but that believers should expurgate from their theology things that have become politically incorrect and inconvenient.

Christians should certainly to be open to change — if they sincerely believe that past interpretations of their faith's founding documents were wrong. But they should not do so based on political expediency, or because public opinion has shifted.

Bruni says that prominent gay philanthropist Mitchell Gold told him that "church leaders must be made 'to take homosexuality off the sin list.'" It's pretty clear that this is among the ultimate political goals of the gay rights agenda. It's also something of a slippery slope in the eyes of the faithful. Why not take premarital sex off the sin list, too?

Well, why not? Because the Christian faith holds the covenant of marriage between a man and a woman among its most deeply important tenets. Period.

This doesn't mean Christians should discriminate against people who have premarital sex, or people who marry someone of the same sex, or any other sort of person who does something that our faith views as a sin. Everyone is entitled to equal protection under the law. But none of that means Christians should change their fundamental beliefs to allow things that have been sins for 2,000 years to suddenly be a-okay.

We can never create a faith that is welcoming and inclusive to everyone, and frankly, we shouldn't try. Change Christianity too much and it is no longer Christianity.

Let's remember, too, that Christianity has a rather stubborn insistence on exclusivity. The notion that Jesus Christ is the only way to eternal life — that other faith traditions must therefore be false — is an inherently offensive suggestion. Should we change that, too?

In Bruni's view, Christianity encompasses ideas and behaviors that "almost everyone deems archaic and irrelevant today." But that doesn't mean Christians should just vote on which things to get rid of. Not if one believes the word of God is permanent. If you don't like it, leave the faith. But don't pressure Christianity to line up perfectly with what's popular today. Especially if you don't even believe in it.