She's a rabbi. He's a Roman Catholic. Come December, the potential for problems is enormous. Should the greeting cards read "Merry Christmas," "Happy Hanukkah," or simply "Happy Holidays"? Add a two-year-old daughter to the mix and things get even more complicated.

For Michal Woll, a Reconstructionist rabbi, and her husband, Jon M. Sweeney, coauthors of Mixed-Up Love: Relationships, Family, and Religious Identity in the 21st Century (FaithWords, $17), the choice was clear. "Our household is Jewish," says Michal. "We don't have Christian symbols there." Before the couple married, there were plenty of discussions about shared values. "It was important to us that there be a clarity of path and to avoid confusion by mixing religions. We decided that our child would be raised in the Jewish faith."

Her husband is just as devout in his religious life, but he practises Catholicism apart from the family. In addition to the occasional early mass during the week, Jon attends services at a synagogue. It's a marriage that shouldn't work, but does. According to Michal, the more a person is involved in their religion, the harder it is to be with someone of a different faith.

Are mixed-religion homes more stressful?
Though we live in a country where religious differences are accepted, the mixing of religions isn't always smiled upon. Michal says she was turned down for at least one job in the Jewish community because her husband wasn't Jewish.

Situations such as this can put stress on relationships. Recently, the couple settled in Ann Arbor, Mich., and are feeling like they are being accepted as an interfaith couple.

A divorce case in Illinois shows just how contentious the question of religion can be for some couples, especially when there are children involved. A Catholic man who converted to Judaism and married a Jewish woman promised to raise their daughter in the faith, then changed his mind. He had his daughter baptized and then emailed his wife a photo of the occasion. He also defied a court order by taking his daughter to mass. The restriction was lifted in a later ruling.

Fortunately, other couples manage to navigate their differences with much less drama. Calgary couple Karri Quan and Jan Rubak have been married for 13 years; Karri is religious, Jan is not. They're part of a growing trend in Canada: According to the 2011 National Household Survey, 25 percent of Canadians say they have no religious affiliation, up from 16.5 percent in 2001. Research shows a worldwide decline in religiosity, with Canada among countries experiencing a notable decline – 12 percent – since 2005.

How do you describe your family?
For Karri and Jan – parents of two daughters, ages four and 10 – harmony came with the dropping of labels. "Early on, in our dating phase, we talked about the differences in our beliefs, our commonalities in terms of morals and values, and about how we would approach parenting," explains Karri, who was raised in the Anglican Church and now attends United Church services. "We have found that, because our way of being in the world is so very similar, labels don't matter nearly as much to us as they seem to for other people."

Karri and Jan don't attend church regularly, but when they do go, it's as a family. Talk about God is commonplace, and prayers at dinner and at nighttime are part of the children's routine. Jan, an atheist, is supportive of the role religion plays in his daughters' lives, and he modifies some rituals to make them more consistent with his own beliefs. Though the girls' mealtime prayers involve thanking God, Jan views them more as generalized gestures of gratitude. "It's not so much the words that are important – it's the message and the intent that matters."

There are awkward moments, for sure. When the couple's eldest daughter was three years old (and wise beyond her years), she liked to pose complex questions such as, Who made God? "In those cases, I'll leave the room and let my wife answer," Jan laughs. "In truth, we preface our answers with, ‘Some people think that…' We are very careful not to make judgment statements. Instead of saying something is right or wrong, we just say it is different. We think it's important to expose our children to different beliefs."

Which holidays do you celebrate?
Christmas is a mixed bag, incorporating Jan's Danish traditions (opening a gift on Christmas Eve) and visiting the nativity scene set up in Calgary's Heritage Park each year by The Church of Jesus Christ of Latter-Day Saints.

The kids enjoy the religious and non-religious traditions equally.  But both parents understand that their daughters will one day have to make a choice: to believe or not to believe. "It will be both a happy and sad time when that day comes," says Karri. "I have to be honest and say I'd be a little disappointed if they didn't continue to believe. But what truly matters is that they make their own decisions thoughtfully, after questioning and considering what they've learned."

What happens if you and your partner divorce?
For divorced parents, being on the same page is even more important. "I read the Bible front and back," says Matthew Hutchinson, a born-and-raised Presbyterian from Paris, Ont., "and when I was married to my first wife I went to church every Sunday with her, even though I had determined by then that religion, by and large, was not for me." When the couple split, his ex-wife married a more devout man. Once that happened, Matthew and his ex sat down and talked about how to make co-parenting their son and daughter, now 14 and 11, work. They decided on a couple of ground rules.

"We are careful not to say the other person is wrong or to be dismissive of a different opinion. We make sure our kids never stress over the fact that their mom and dad don't share the same beliefs," says Matthew. When his kids are with him, they still pray. "I don't pretend to pray with them. I give them the respect and freedom to do whatever they feel comfortable with."

"In the end, don't we want our kids to be open-minded about the world?" asks Toronto psychotherapist Lori Dennis. "It's healthy for kids to learn, to read, to look for meaning and be curious." Where mixed-faith parents fail is in using religion as a form of power play: as a way of getting children to agree with them – and disagree with the spouse – regarding what's right and what's wrong. This can be very confusing for kids.

Christmas can be used to expose kids to different beliefs. It's much more healthy than an autocratic approach in which one religion is presented as the only right way to live or to celebrate. "Blind faith is problematic," says Dennis. "Children raised in those types of environments have difficulty coping with life outside of their religion. They have trouble thinking outside of the box. Teaching them to embrace and respect differences is a wonderful gift that opens their world."

Religious etiquette over the holidays
Q: Your holiday hosts say prayers before dinner, even though it's not your practice. What do you do?
A: As a guest in someone's home, you need to be respectful. It's fine to simply bow your head and not recite the words.

Q: Friends celebrate both Christmas and Hanukkah. What type of card do you send?
A: A blank card (think winter scene) with a message tailored to that
family works best. Wishes of peace, love and joy are fitting during the holiday season.

Q: When visiting friends who don't celebrate Christmas, is it OK to bring a gift?
A: You can. But present it as a gift for the host, not a Christmas gift. Keep it generic, like a potted plant, gourmet biscuits or a coffee-table book.

We have more parenting tips, including how to avoid fights with your partner over the holidays. 
                                               

This story was originally titled "A Matter of Faith" in the December 2013 issue.             Subscribe to Canadian Living today and never miss an issue!