Growing numbers make changes to ceremony that takes place on eighth day of boys' lives and is one of Judaism's oldest rituals

When his pregnant wife first challenged circumcising their son, Mike Wallach had a gut reaction: "That's what we do, we're Jews!" But doubts about whether the surgery was medically necessary and concern over his wife's opposition forced Wallach to confront some questions.

Can you be Jewish without Judaism's oldest ritual? he wondered. What does it mean to be Jewish?

Speaking with God, the 37-year-old screenwriter and grandson of Holocaust survivors explained he was using the "free will and brain you gave me" to reject circumcision. God, he concluded, wouldn't be impressed by the desire to do something simply "for tradition's sake".

"I wasn't at peace until I had that conversation," said Wallach, who grew up in Washington and now lives in Brooklyn.

Wallach is among a small but growing number of Jews who are slowly altering what has for millennia been considered perhaps Judaism's core rite. The Bible says an adult Abraham circumcised himself to mark the covenant between him and his descendants and God. Any male who doesn't circumcise, God says in Genesis, "that soul will be cut off from its people; he has broken My covenant".

Many of these Jews, according to rabbis and the ritual circumcisers known as mohels, are rejecting the classic festive circumcision ceremony, called a brit milah, or bris. For thousands of years, Jews have performed the ritual removal of the penile foreskin on the eighth day of a boy's life, sometimes at the cost of death during periods of antisemitism.

A very small percentage, including Wallach, are not circumcising at all. Others, uncomfortable with the joyous, public ceremony around an intimate surgical procedure, are circumcising their sons in the hospital and crafting new baby-welcoming ceremonies days or weeks later for family and friends. Some are having no public service at all.

Meanwhile, there is an unprecedented level of debate among friends, grandparents and couples about whether to circumcise and how. Given that the topic merges sex, religion, identity, culture, gender equity, health politics and antisemitism, such discussions can grow intense or acrimonious.

"What's a nice word for the Bermuda Triangle?" said Rabbi Shira Stutman of Sixth & I Historic Synagogue, Washington's largest community of 20- and 30-something Jews. "Circumcision is at the nexus of everything that it means to be Jewish ... It's primal. It's deeper than anything we can understand rationally."

Sixth & I gets so many questions about circumcision from younger Jews that it will hold a class in early 2014, Stutman said. While the vast majority of Jews decide to circumcise, she said, "the days of being 100% sure and not even thinking about it are done". Stutman opted for a private ceremony when her son was born.

Several factors are fuelling the trend, including growing secular discomfort with the practice, mixed data on medical necessity and an American culture increasingly open to reinterpreting religious practices. The percentage of circumcision procedures among the general population is also dropping.

American Jews, on the whole, are now more immersed in secular culture and thus more apt to look askance at the idea of a tribal scarification ceremony. High education levels and a natural aesthetic are also prompting questioning among younger Jews.

"Because the American Jewish community is significantly educated, they're more likely to do organic and wanting everything to be natural, and a bris is sort of primal and ancient," said Julie Pelc Adler, director of the circumcision programme for Reform Judaism, the largest US denomination of Jews. "It's really different than the aesthetic of, 'Oh, let's bring this perfect new baby and swaddle him in perfection.' It's looking at this perfect baby and saying, 'He's not perfect, we need to do this one thing.'"

Rabbi Shira Stutman discusses circumcision at a class for converts to Judaism at the Sixth & I Historic Synagogue in Washington. Photograph: Linda Davidson/The Washington Post

Ben Rempell, 35, didn't consider himself particularly religious. So the USAid employee was surprised at the force of his reaction in November 2009, when one morning his then-pregnant wife, Danielle Rudstein Rempell, lobbed this question: "Isn't circumcision another form of genital mutilation?"

Rempell remembers "giving her a disgusted look" and becoming defensive and angry. He became more so when she raised the question with their weekly Sunday dinner group.

He began to struggle with it on his own, unsure why the rite was so important to him given that he was not a particularly observant Jew.

Ultimately, he discovered, his motivation was more tribal.

"It wasn't a Jewish thing, it was an identity thing, envisioning growing up and he sees me and I see him and he asks why he's different. A child's identity is their family," he said.

But isn't Jewishness part of your identity?

"It had to have something to do with Judaism. That's what we do. That's what I am," said Rempell, who now lives with his family in Honduras.

His secular-but-tribal argument for a son "who looks like his father" convinced his wife. They now have two sons, both circumcised – but with no ceremony.

Not all couples get on the same page. Several couples interviewed didn't want their names used, either because their disagreement was so intense and they wanted to put the issue in the past or because they were expecting and didn't want family and friends to be drawn into their private debate. They tell similar stories of angrily emailing American Academy of Pediatrics studies, painful conversations challenging each other's concepts of Judaism and even circumcisions ending in tears and fights.

Four statements from the American Academy of Pediatrics, the largest US body of children's doctors, have wavered back and forth a bit since 1979. Most recently, in 2012, the group said benefits outweigh potential risks but not enough to recommend circumcision routinely. Organisations that have done the most extensive polling on US Jews say there is no data on circumcision rates.

Binyamin Biber, a rabbi of the small movement called Secular Humanistic Judaism, is perhaps the only rabbi in the Washington area who advertises his willingness to bless a welcoming ceremony for a boy who is uncircumcised. Requests for his services are small but growing, from one or two each year in the past to four or five a year now.

He sees questions about circumcision as a natural product of a time when more and more families are interfaith and parents aren't sure about a ritual once rooted in special treatment for boys. The liturgy he uses doesn't mention God and emphasises bringing the child into a "human covenant for a better world".

"We live in a more cosmopolitan world and Jewish families have become very intercultural," said Biber. "For those families, a ceremony which regards Jewish males as privileged seems problematic, to put it mildly."

Rabbis who are engaging Jews' questions about circumcision are asking people to think about the ritual in a different way. "We do all sorts of things that hurt our children that help them for the greater good. We vaccinate them, we ground them, we take away their devices," Stutman told a wide-eyed class of adults converting to Judaism one recent night as she ran through the circumcision curriculum.

Several people in the class at Sixth & I gasped when she explained that even when circumcised men convert, they give a few drops of blood from the penis to represent their commitment. "Remember we are an earthy people! We don't pretend we don't have bodies!"

Adler said the circumcision issue is just part of a world of questions about bringing Jewish ritual and law into a new era. She fields questions, for example, about whether the male child of a lesbian couple whose birth mother is not Jewish – but whose other mother is – would be considered Jewish, or would the child need a conversion component of his circumcision ceremony.

Judaism generally was passed to children through their biological mothers. But in recent decades more liberal Jewish denominations have been recognising biological fathers as well.

When it comes to religious evolution, she asks, "where is the line? At what point is it no longer Judaism? Each choice distinguishes Jews, and it's a slippery slope."

This article appeared in the Guardian Weekly, which incorporates material from the Washington Post