About one in four Americans (27 percent) who are married or living with a partner are in "religiously mixed" relationships. That's the word for this Valentine's Day from the Pew Forum on Religion & Public Life, which mined data from last year's huge U.S. Religious Landscape Survey. When people from different Protestant denominations are included in the calculation, the intermarriage rate rises to 37 percent.My reaction? That still sounds low. I haven't burrowed into their stats, and perhaps the trend is toward intermarriage among younger cohorts. Fifty years ago intermarriage was in the single digits, as religious denominations were like tribes, and geographical stability played a big role in choosing partners. (And beliefs, of course: How can you marry someone who is going to hell? Well, unless you're Mel Gibson, who fears his Episcopalian wife is damned.)That has all changed, of course, but perhaps not as much as I thought. Certainly the Jewish community has for years seen intermarriage--perhaps as high as 50 percent--as a grave threat. The Jewish intermarraige rate, as shown by the grafic below, is 31 percent--okay, but not great. But I'm kvelling over the Catholic rate, which at 22 percent is surpassed only by the Mormons and Hindus.Does this ring true for your experience? Also, how many of these partnerships between Catholics were sealed in church weddings? The rate of Catholics marrying in church is falling. Does having a spouse of the same faith matter? Or is it the intensity of one's belief--or lack thereof--that is important? Is it more important to be of a similar religious temperment, no matter what the religion? The arrival of kids into the mix also seems to be a monkey wrench if the faith issues hasn't been sorted first.For all sorts of reasons I'm glad my wife and I are both Catholics, both practicing. But I know of so many wonderful interfaith marriages, and lots of same-faith unions that are a disaster. Just a few conversation-starters to throw out during that candlelit dinner tonight. (Takeout here. Who is crazy enough to go out on Valentine's Day?)