A cultural shift in thinking about parenting and gender roles has led to a surge in divorced couples agreeing to more detailed shared custody arrangements that increasingly spell out how they will practice and talk about their religious faith.

Agreements of the past stuck largely to the question of where the kids would spend such holidays as Christmas, but today such accords can stipulate religion, denomination and doctrine. Episcopalian, not Catholic. Sunday school through high school, no stopping earlier. Agreements even clarify which parent will pay for a bar mitzvah and which controls its guest list.

But can parents predict down the road what will be important to them, or even what they will believe, to the level of certainty that can be expressed on a piece of paper that can be enforced by a judge?

“The thing that has to be impressed on parents is, you don’t want to confuse your kid,” said Darcy Shoop, a Rockville divorce attorney who recently crafted a settlement that bars one parent from celebrating Christmas with her children in their home. “You have to be careful with this stuff.”

For the 14 years Marsha Lopez, who is Jewish, was with her former husband, a Catholic, their different religious backgrounds played out in scenes like this: a wedding led by a priest-rabbi team, Star of David Christmas tree ornaments made of pipe cleaners, interfaith holiday cards.

Not a lot needed to be said, the 38-year-old Bethesda epidemiologist recalled last week. “We were on the same page.”

The custody agreement the couple worked out last year gets a lot more specific. The document bars either parents from speaking critically of the other’s faith and from “sharing their religious experience” in a way intended to make the children think they are “one or the other,” either Catholic or Jewish.

Although such detailed agreements might seem cold and awkward, they help families of divorce, parents and divorce professionals say. They can stave off fights and ease more challenging periods, such as holidays.

December has its own set of sometimes heartbreaking faith issues for separated families.

Lopez bought herself a Christmas present this year after her 5-year-old daughter worried that there were no gifts for Mom under the tree. Because Lopez is Jewish, her own family didn’t give her Christmas gifts, but Lopez still puts up a tree because that’s what she did for years with her ex.

“She said, ‘Isn’t Santa going to bring something for you? You don’t have anything,’ ” said Lopez. “I got myself a to-go French press coffee cup and wrapped it.”

The most painful aspect of the holiday, she said, was when her 7-year-old son asked how Santa would know to bring presents to her house Friday morning, when Lopez celebrated Christmas with the children because they would be with their father for the actual holiday.

Religion is, of course, just one topic in the new, more exhaustive agreements. Others include plans for education, parental dating, discipline and whether medication can be given for a yet-to-be-diagnosed learning disability.

The typical divorce now includes a parenting plan, created by professionals called parent coordinators.

When Ben Demeo, a District accountant, divorced six years ago, he and Regina, his former wife, agreed the custody arrangement would match how they had lived together, with her largely defining their son’s faith identity. At her request, the agreement says the boy, now 8, will be raised Episcopalian, her faith. Ben Demeo is not required to take the boy to church on the Sundays when the two are together.

The Demeos’ split was amicable, and they sometimes spend Easter and Christmas Eve all together. But they still felt it was important to put the details on paper.

“Let’s say he gets married to someone who is Jewish, and all of a sudden he’s going to synagogue — I’d have an issue with that,” said Regina Demeo, 39, herself a divorce attorney. The boy “is already baptized; it’s set in stone.”

Ben Demeo, 43, said he has no issue with the wording in the agreement. He describes himself as a Christian,but not one who is aligned with any denomination. “I decided only one can’t be right.”

When his son eventually asks questions, “I’ll tell him honestly my beliefs. . . . I suppose if we started attending Roman Catholic Mass or Methodist services, I guess she could object, but I hope that would not be an issue.”

Although religion typically is included in custody deals, it usually is not the most contentious issue, some experts said.

Some attorneys say disputes about religion are more common in interfaith marriages, while others say the opposite.

“For parents who feel strongly about their faith, and during the holiday the child is with the other parent who doesn’t go to church, it can be a flash point,” said Gail Thornburgh, a Bethesda psychologist who helps people create parenting plans.

“Sometimes, when people get divorced the religious aspects become significant. People who didn’t go to church or mosque all of a sudden need to and to bring their children,” she said.

Some custody agreements purposely use vague wording that requires parents to come back to the negotiating table if a disagreement arises.

Paul Reed, 39, an attorney who lives in Alexandria, said his divorce in 2007 was “not necessarily amicable.” A devout Anglican from a family of Canadian bishops, Reed said during the marriage it was “unspoken” that he would be the one to answer their now 7-year-old daughter’s questions about faith. His ex-wife was born Catholic but wasn’t religious during their relationship.

Their agreement says only that the two will “jointly make decisions about education, health and religion.” It requires them to resolve questions together or with professionals in an effort to avoid court.

Then last year, his ex started going to a Catholic church again and became confirmed.

“I told her, ‘You need to figure out the differences [between Catholicism and Anglicanism] so when she has questions we can answer,’ ” Reed said.

They alternate who spends Christmas with their daughter.

Some veteran divorce lawyers say the simple question of who gets the holidays has become less of a focus as people become accustomed to joint custody and sharing.

No document, no matter how detailed, can substitute for being together during a key community moment. Lopez said she feared having a “nervous breakdown” being home on Christmas for the first time without her kids.

She left Friday evening for Paris.

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