Commentator Patrick J. Buchanan was twice a candidate for the Republican presidential nomination and the Reform Party's candidate in 2000. He served three presidents and is the author of seven books. He now chairs The American Cause, a conservative group that advocates for national sovereignty, limited government, and traditional American values.

Buchanan talked with Beliefnet's religion producer, Deborah Caldwell, about his controversial new book "The Death of the West."

Why do you assert in your book that America is being de-Christianized?

Certainly the Supreme Court has thoroughly de-Christianized the public square and the public schools. It's undeniable. You can't put up a nativity scene in a public park without the ACLU having it torn down. Crosses that commemorate war veterans who have been killed have been taken down. I think there's been a thoroughgoing de-Christianization of public institutions, the public square and the public schools. There are no longer Christmas carols, Christmas plays and Christmas celebrations in the public schools. Easter was removed a long time ago. That's the public realm.

In the private realm, I think America is really almost a post-Christian nation. Sure, there are tremendous numbers of devout Christians-evangelicals, fundamentalists, and traditional Catholics--but at the same time, I think a huge slice of America is only nominally Christian..In people's hearts and minds and souls, I think, the traditional moral code no longer is as binding on as many people as it was in the 1950s and early 1960s.

But was America ever really all that Christian anyway?

There's no doubt that in the post-war era, all the Catholic seminaries were filled up. All the Catholic schools were taught by nuns. I didn't have a lay teacher in a single class in my grammar school, and every homeroom teacher I had in high school and college was a Jesuit. The nuns have now almost vanished and I think the median age of Catholic priests is now 65. And it's undeniable that in terms of church attendance, in terms of vocations, the Catholic Church in America is in a very deep crisis--and it's in a deep crisis in Europe. And the strength of the converts is in the Third World.

Yes, Christians talk a lot lately about the idea of Christianity strengthening in the developing world. And these new Christians are now becoming missionaries to secularized Americans and Europeans.

I think the West is increasingly becoming mission territory. Speaking as a Catholic, I find that a good thing. That's what the West needs, or it's not going to survive.

And I do think this: what I have found is that wherever faith dies, the culture dies, and the country and civilization begin to die. For example, people say it's affluence causing the depopulation of the West. But the point is, Russia is a poor country and it is dying and Utah is a very wealthy state and it is booming because of the very strong, healthy faith-the Mormon faith-of the folks in Utah. And white folks in Texas have a higher birth rate than the white folks in California, and it's because Texas is part of the Bible Belt. If you take Asia-the Philippines, which is Catholic, has a rising birthrate, but the Japanese birthrate is declining and their faith is dying. And there's not a single Islamic country I could find whose population is not growing or exploding. So I think the correlation between faith and rising populations is absolute.

But you also say immigration causes trouble for this country.

First, the folks who come here--the longer they stay here, the more they succumb to the popular culture, the dominant culture, the MTV culture. Secondly, the folks from Asia and from the Middle East are predominantly non-Christian. Third, those coming from Mexico--the problem is not the religion, the problem is they're not being assimilated into an English-speaking country and to our culture. They're retaining their language, they're retaining their culture, their civilization, their TV, their radio--and their loyalty--to a foreign government. This is the problem of the immigration coming from the south. It's not the religion--it's the failure to assimilate.

But if they're Christian, they're starting Korean Presbyterian churches, for instance...

Some of them are starting churches, but the problem here is in language and assimilation into an English-speaking nation and American culture. What you're liable to end up with is Balkanization. The Serbs, for example are devoutly Orthodox, and the Croats are devoutly Catholic, but no assimilation has taken place between them. And so what I'm saying is that religion alone is not enough. Religion is one component of a nation, usually. But it's not enough. Language is almost more important.

But if people are then learning English and remaining devoutly Christian...