When people of different belief systems join together, are they likely to break apart? Statistics say so, showing mixed-religion marriages three times more likely to divorce. Yet marriages between couples of different religions have increased steadily over the past few decades.

Some Facts About Interfaith Marriage

In a 2010 survey, 45 percent of of U.S. marriages in the previous 10 years were between people of different faiths or clashing denominations within the same faith, such as Catholics and Protestants. Overall, 25 percent of all marriages qualify as interfaith. That figure is up from 14 percent in the late 1980s. According to a 1993 study by economist Evelyn Lehrer, marriages between Jews and Christians have a 40 percent chance of divorce within five years. That compares to 10 percent for the overall population. Half of marriages between evangelical Protestant Christians and non-evangelical Protestants end in divorce.

Factors Behind the Rise in Interfaith Marriage

Couples are less likely to discuss religion with their partners prior to marriage than other topics. People are marry partners with conflicting political views more often than different religions. But in U.S. society, political opinions are a popular topic of conversation, so political differences may get more attention. Americans also get married older than ever before, allowing them to drift away from family traditions, including religious ones. However, when children enter the picture, religion often rears its head again.

Children: The Problem, Not the Solution

According to researcher Naomi Schaefer Riley, interfaith couples to whom religious differences seem unimportant often have a sudden change of heart when it comes to raising kids. Couples will agree to raise their children in one faith or the other -- the mother’s faith wins out two times as often -- only to find that when it comes time for religious holidays or other traditions, the parent whose faith gets left behind can’t adapt. In fact, studies show that interfaith couples don’t often argue about religious points, like whether Jesus was the Son of God or not. Their disagreements are almost always over family traditions in child-raising.

Religious Tolerance on the Rise

More liberal religious attitudes also contributes to rising interfaith marriages. The Catholic Church once required non-Catholics marrying into the religion to raise their children as Catholics, but that requirement was dropped. In the UK, where Islam is the fastest-growing religion, 21,000 interfaith marriages involving a Muslim were recorded in 2001 with the numbers rising since then. While Muslim men are permitted to marry Jews and Christians under most interpretations of Islamic law, women are not. But even that attitude may be changing, with some Muslim clerics arguing that the Quran does not forbid women from marrying outside the faith. Young adults born in the last three years are less likely to identify with a specific religion, and that may be the best hope for the future of interfaith relationships.