In hindsight, Dr. Charles Selengut’s 2003 book, “Sacred Fury: Understanding Religious Violence,” didn’t talk enough about Buddhism.

It’s an oversight that became increasingly clear as his book was adopted in classrooms around the world — and when Buddhist monks played a leading role in ethnic violence in Myanmar that killed 200 people in 2012.

And it’s an oversight that has been fixed in the new third edition of the book, which came out earlier this year.

Dr. Selengut, who lives in Teaneck, is a professor of sociology at the County College of Morris. “Sacred Fury” tries to understand religious violence through the lenses of sociology, psychology, and theology. His thesis is that violence carried out in the name of religion cannot be separated from the religion itself.

“Some is pure religion, some is the interplay of religion and politics, but it’s incorrect to say that religion has nothing to do with violence,” he said. “All religions have elements that encourage violence against those who disagree with them or challenge their theology.

“If someone says Islam has nothing do with religious violence or jihad, they don’t know what they’re talking about,” he continued. “Look at the sermons in mosques, and you can see how they’re encouraged to do violence.”

Even violence not directly motivated by religion can be legitimized by it, Dr. Selengut said. “Think of Hinduism. Hindu nationalists want to be certain that India remains a Hindu country, so the masses are encouraged to take action against any religions that aren’t Hindu.

“Ordinarily, Hinduism and Buddhism are viewed as religions of nonviolence. But the reality is there have been major killings in Hinduism and Buddhism.”

How is that possible?

“If the religion is threatened and the motivation of the violent religious people is not just out of anger, but is for the religion, that’s not called violence,” Dr. Selengut said. “The violence is reinterpreted as nonviolence.

“In Hinduism, if someone undertakes violence to protect the Hindu gods or institutions from a pure motivation, not from personal anger or rage, that killing is considered sacred killing. That put it into an entirely other realm.

“It’s a kind of dichotomy in the religion. People in the West often don’t know about it. You can have people so anti-killing that they’re vegetarians, yet the same adherents of the religion can be very violent against those who challenge their beliefs.”

And of course, religious violence is not coming just from Hindus and Buddhists.

One addition to this edition of Dr. Selengut’s book is a discussion of ISIS.

“There is an international Muslim movement based on their ideology, which argues that Islam needs to be the leading religion all over the world, that Islam has to be the progenitor of morals and government authority.

“Often, the religion’s scriptures themselves encourage violence,” he continued. You just have to listen to what ISIS says.

“Or the extremist Christians who kill abortion doctors. In extreme anti-abortion groups this is considered legitimate theology. The Christian advocates against abortion doctors call it the Phineas Option. You’ll know it from Pinchas in the Torah. Just as in the Torah Pinchas killed Zimri” — acting zealously for God’s sake without a specific Divine command — “they use this as the ultimate religious justification.”

So why is this upsurge in religious violence happening now?

“I wish I could answer that question,” Dr. Selengut said.

“One reason is the movement of globalization. As long as religions stayed in their own enclaves, there was no need for any interaction between different religions. Often religion renews itself. It goes in cycles. Religions become more moderate. Over time the essentials reassert themselves. We see that in contemporary Judaism as well. After a modernization of American Judaism, the internal life of Judaism moved back to the fundamentals.”

And religious fundamentalism leads to religious violence.

“Because its beliefs are so strong, fundamentalism doesn’t permit pluralism or diversity,” Dr. Selengut said. “There is only one truth, and we must protect that truth. That feeling of us against them, that we are right and everybody else is wrong, permits the elements of a religion that do encourage violence to come forth. There are notions of violence in all religions but often they’re dormant. With fundamentalism these elements are rediscovered. That encourages the violent outbursts.

“We see that even in Judaism. In Meah Shearim recently, they beat up a soldier with peyos, because he was charedi but joined the army. Fundamentalism gives such power.”

What can be done to stop religious violence?

“It has to be two-pronged,” Dr. Selengut said. “A lot of it is up to the religious leaders themselves. The people who know the texts, who are part of the tradition, have to stand up and say that violence is a misreading of the tradition, an exaggeration.

“All the statements against religious violence in the New York Times don’t mean anything. When an iman who has standing as a very religious and learned and sacred figure takes on religious violence, that would have power.

“I think it’s the same thing in Judaism and Christianity. Religions can only be transformed internally. It can’t be transformed by outsiders who are not privy to the theological thinking of a religion.

“The other prong is practical. When people break the law or engage in violence, government authorities have to stop them.”

Do different religions have different limitations in how violent they can get?

“There’s enough in each religion so that astute students of the religion can probably legitimate any kind of violence,” Dr. Selengut said. “In Judaism, the terrible, heartbreaking example would be Yigal Amir, who assassinated Prime Minister Yitzhak Rabin. There were those who said there was a group of rabbis who legitimated what he did.

“It’s the same thing in other religions. The vast, vast majority of Christians are against killing abortion doctors, but there is a subset that would define that as legitimate.”

Dr. Selengut said the roots of religious violence lie in the nature of religion.

“Religion is different than any other kind of commitment, because religion has to do with what is the ultimate truth,” he said. “I take it on faith. I don’t have to logically or rationally defend what I’m doing. What I do religiously partakes of another calculus, another reality, a truth beyond rational or ordinary life. I don’t have to consider other elements

“For example, in politics, considering whether to bomb Syria or not — I have to think what are the consequences, politically, economically, internationally. It’s a rational calculation. In religion, I’m not bound by these calculations. I know that it’s true, I do it, and God told me to do it. I don’t have to worry about logical objections and rational considerations.”

Dr. Selengut isn’t sure what his next writing project will be.

“I’m thinking about trying to do more storytelling,” he said. “I’m thinking of doing a bit of memoir about my own childhood. What it meant growing up in the ‘50s. How the Jewish world changed.

“I grew up on the Lower East Side of Manhattan. My parents were second generation Americans. Orthodox Jews were a minority of a minority. When I was a little boy, when they said Yizkor the shul was packed. People left work to say Yizkor. Their grandchildren wouldn’t do that.”

That’s not the only transformation Dr. Selengut has seen.

In high school, he studied with Rabbi Yaakov Kamenetsky, who was one of the leaders of American charedi Orthodox Judaism until his death in 1986, and whose son is a leader in that community today.

The elder Rabbi Kamenetsky was born in Lithuania in 1891.