Inter-faith marriages are three times more likely to experience break-up compared to single religion marriages, 
according to a story in The Washington Post.
The report cites a Religious Identification Survey which 2001, which showed that people who had been in mixed-religion marriages were three times more likely to be divorced or separated than those who were in same-religion marriages.
Research shows that the phenomenon of mixed religion marriage is growing, the report says. According to the General Social Survey, 15 percent of U.S. households were mixed-faith in 1988. That number rose to 25 percent by 2006, and the increase shows no signs of slowing.
The American Religious Identification Survey of 2001 reported that 27 percent of Jews, 23 percent of Catholics, 39 percent of Buddhists, 18 percent of Baptists, 21 percent of Muslims and 12 percent of Mormons were then married to a spouse with a different religious identification.
Young people are also far less likely to worry about the impact of marrying someone of a different faith background. Less than a quarter of the 18- to 23-year-old respondents in the National Study of Youth and Religion think it’s important to marry someone of the same faith.
According to research published in 1993, if members of two mainstream US Protestant denominations marry, they have a one in five chance of being divorced in five years. A Catholic and a member of an evangelical denomination have a one in three chance. And a Jew and a Christian who marry have a greater than 40 percent chance of being divorced in five years.
Even differing degrees of religious belief and observance can cause trouble, research suggests. For instance, a 2009 paper published by the University of Texas, found higher rates of divorce when a husband attends religious services more frequently than his wife, as well as when a wife is more theologically conservative than her husband.
However, modern couples seem unaware of these risks, partly, the report suggests, because they are getting married later in life. And the period between when children leave their parents’ home and when they start a family is a religious downtime.
Today, the median age of marriage for American men is 27, and for women, it’s 26 — by the time wedding bells ring, many young people don’t think of themselves as religious.
A recent Pew survey on the millennial generation shows that adults ages 18 to 29 are less likely than previous generations to affiliate with a religious group and tend to pray less often than their elders. Their beliefs about the certainty of God’s existence and life after death, though, are not so different from their parents’ and grandparents’. And in the National Study of Youth and Religion, most of the respondents say they plan to become more religious when they get married.