What do you do if you start to realize that you simply cannot live in the culture that surrounds you?

If you come to understand, slowly at first and then with increasing speed and no little horror, that your world doesn’t have the right kind of oxygen for your lungs to breathe? That you will choke and sputter and eventually cease to be if you stay there?

That you have to leave your whole life behind — your wife, your children, your parents, your siblings — and that you risk losing them forever?

You have to be really certain that you cannot live as you have been living to risk ending your life as you know it.

Shulem Deen, left, as a Skverer chasid and right, as he looks today.

Shulem Deen, left, as a Skverer chasid and right, as he looks today.

That’s what Shulem Deen did, as he chronicles in his memoir, “All Who Go Do Not Return,” and as he discussed in a recent phone interview.

His world was New Square, in Rockland County; he was a Skverer chasid, a transplant from Brooklyn, the son of people who had made their own way to the chasidic world. He had been an enthusiastic chasid, a true believer, even an enforcer, someone who kept an eye out for other people’s infractions.

But he also had doubts, and as they filtered into his mind they expanded and tormented him, and eventually pushed him out.

Mr. Deen is a heretic now, he says, but he still is a Jew. He is a gifted writer too, so his memoir — unlike so many others from people who are off the derech, who have left the straight, clearly marked path that was laid out for them — is not filled with cartoon villains and gaudily signposted emotional reactions. It is, instead, the rueful, painful, deeply reflective story of a man whose heart and brain, working together, left him no option but to quit the only life he’d known.

The narrative is fairly straightforward. Mr. Deen, the child of a brilliant but troubled father, who died young of what seems to have been anorexia nervosa, who loved his children but loved his studies and his communion with his God more, and a mother whose story he leaves largely untold, clearly out of love, was himself (as he does not say but anyone reading his story must see) brilliant. He was avid in everything he did, and after some early missteps he planted himself firmly in the Skverer world. He married a woman he did not love, after having met her once, an episode he describes in cringe-making detail in his book. (In his book, he mentions her only respectfully; she is, after all, the mother of his children.) He had five children; he would have had more if he had not refused, because he could not support them.

None of his children speak to him today; he hopes that some day that will change. What has not changed is his love for them. That will never change.

In conversation, Mr. Deen talks about the community he left.

One of the basic problems it faces is that it is not economically sustainable, he said. Young men are expected to continue their studies of Jewish text, even after they are married, even after they become fathers. They are given stipends, but there is no obvious source of funding beyond government aid.

“Historically, the men used to work,” Mr. Deen said. “In the 1950s, the 60, the 70s, even the 80s, there were hundreds of chasidic men working in places like the diamond district. Mostly, they wouldn’t go to college; they wouldn’t be professionals, but they would do things like diamond cutting, skilled labor. Some would — computer programming and engineering would be a little on the fringe, but acceptable. Accounting was acceptable.”

To some extent that still is true, he said, but most of those jobs require training, even college, and such education is discouraged. Instead, “mostly you get a job within the community — a low-paying job — or you study in a kollel and get a stipend for that.

“As an economic model, I think that it is very poorly thought out. It seems like there is nobody giving serious thought to how this is going to play out over the next few decades. People are making choices for themselves. Some young men in Brooklyn are deciding that they will go get college degrees. What is really sad is that they decide that after they already have three children.

“Things are changing, but I don’t think the model is sustainable. I think we will see an organic evolution, but there will be some painful periods, and some casualties.

“Chasidim used to have a stronger work ethic,” he continued. “There was not this wholesale reliance on government benefits. My understanding is that they had not become as sophisticated as they are now in incorporating government programs in their economic model.

18-2-shulem-deen-book-cover“In New Square, the first thing every young couple does is apply for food stamps and Medicaid,” Mr. Deen said. “That’s true of every family, and it is absolutely a matter of course. When I got married in 1993, my kallah” — his bride — “already had taken care of it. It is one of the women’s jobs. In preparation for marriage, the kallah goes to the social services office and applies for food stamps and Medicaid. That’s how it works.

“So what happens is that you present people with the idea that this is doable, that you don’t need to get a college degree, that we will give you some money, and there is some help from the government, and you are young and think that it makes sense. And then you have kids, and you see that it does not work. And what do you do now?

“It is devastating to many people to realize that they do not have options.”

So that is the economic pressure under which people live. There is also the pressure from the outside world pushing in on them.

“The Internet is seeping in,” Mr. Deen said. “They are putting up ever taller barriers, but the barriers are not solid. They are not concrete.” No matter what strictures the community tries to enforce, some people find a way around them, he said.

He talked about other specifics of life as a Skverer. The issue of men and women walking on opposite sides of the street, which, he said, had been limited to New Square but now is finding its way to Kiryas Joel, “started around 2000, when the signs first went up.

“The interesting thing is that at first the signs were not official,” he said. “I remember how it happened. One person in New Square decided that it would be a good idea, kind of like a public service. Nobody liked it when the genders get mixed up on the sidewalk, and this way it would be like on the subway, where the signs say one side for up and one side for down. It was men on this side, women on the other. It was a convenience.

“The sign went up and nobody objected. What kind of objection could the chasidim of New Square have? So eventually it just became a fixture, and now it is there.”

In general, the strict gender separation is in place because “it goes straight to the fear of sex and the power of sex,” he said. “Women represent sexuality to religious men and to the codifiers of religious law. To the ultra-Orthodox chasidic men of today, it can be a 90-year-old woman or a 3-year-old girl. They all represent sexuality.

“When you are a 15-year-old boy and you are told to repress every notion of sexuality, and you are so afraid of your own hormonal urges, it is natural that when you walk on the street, you keep your eyes averted from everything female. You just don’t want to go there. It can destroy you forever.”

There are some advantages to being a woman in that culture, though. “I have two sons, and neither one could have a conversation in English,” he said. They cannot speak, write, or read English.

“My daughters can. The boys study Talmud from 6 in the morning to 10 at night. The girls do not get a good or robust education, but I could take my daughters to the library in secret and they could read there. They know something about the outside world.

“The gap between the girls and boys in their knowledge of the outside culture is tremendous. Because there is so much separation between the genders, they inhabit different worlds.”

Mr. Deen did not leave his community because of its failing economic model or its strictures about gender separation, though. He left it because he stopped believing that the world was constructed in the way that he was taught it was. He stopped believing in God, and when he lost that belief, he lost everything that the belief supported.

“It is psychically and morally destructive to live like that,” pretending to believe something when you really do not, Mr. Deen said. “The real shame is that there are hundreds of people in that same place, but they can’t make the move out. They just can’t. That’s what’s really terrible about trapping people in an environment that is so rejectionist and isolationist, with no way out.”

Still, though, Mr. Deen is Jewish. “My Jewishness — not my Judaism but my Jewishness — is the most important part of my identity. Maybe my maleness is even more important, but my identity as an American, a New Yorker, a Brooklynite — nothing is more important than my Jewishness. I have had to find a way to embrace it, to find a way to celebrate my Jewishness, things related to Jewish culture and history and peoplehood, things that are separate from religion.”

Sometimes Mr. Deen does go to shul, almost despite himself. At the end of the book, he describes himself in a liberal Upper West Side synagogue on a Friday night, listening to the words and music of kabbalat Shabbat, holding the siddur, crying, his tears dripping down onto the page, blurring the words, words that of course he has no need to read because they live deep inside him. (Although he does not mention it in the book, that shul was Congregation B’nai Jeshurun, which is known for the intensity and beauty of its music.)

“Prayer is a meditative experience. There is something about the mythological that human beings always have been attracted to, and prayer is the essence of it,” he said. In fact, he has looked for spirituality in other places, outside the formal Jewish world, but has not been able to find it there. The earnest self-consciousness of spiritual seekers put him off.

“For the first few years, I just didn’t know how to hold these two sides” — his yearning for Jewish expression and his rejection of his past — “in one. I didn’t know how to contain them both.

“But now I live with that tension. Living with tension is a challenge, but as modern people, it’s something we have to do. There’s no real way to get away from it.”