AMNA NAWAZ: Historically, few Ultra Orthodox Jews have served in the Israeli army, a fact that sparked resentment and contributed to recent anti-government protests.

But in the two weeks since Hamas' attack on civilians in Southern Israel, more than 2,000 young men from this religious community have volunteered to serve.

Leila Molana-Allen has that story.

LEILA MOLANA-ALLEN: As Israel prepares for a ground war, more than 300,000 reservists have been pulled up to serve.

Many haven't fought for years or only completed basic training.

Getting them all up to speed is a huge challenge.

PETER LERNER, Spokesman, Israeli Defense Forces: Could be training for tunnel mobilization, knowing how to maneuver in a tunnel and how to conduct combat in tunnel.

Or it could be how -- mobilizing in urban areas, which was also a specific challenge in itself.

So there's a lot of up -- I would say upskilling is the word.

LEILA MOLANA-ALLEN: But some of the new recruits will have no baseline military skills to up.

The Haredim, or Ultra Orthodox Jews, make up about 15 percent of Israel's population, and are its fastest growing community.

They don't traditionally undertake military service, instead believing that they serve by having young men between 13 and 22 to commit to full time study of the Torah, which casts a protective net over Israel and Jewish society.

Earlier this year, the "NewsHour" was on the ground as protests against Prime Minister Benjamin Netanyahu's extreme right coalition government swept through Israel's cities.

This was one of the demonstrators' chief grievances.

Some secular Israelis felt their young people were being sent to serve their country, while the Ultra-Orthodox, as they saw it, got a free pass.

DOR NADLER, Israeli Protester: Some of us are feeling like we are carrying the weight of our country, while other people are just benefiting from it.

LEILA MOLANA-ALLEN: In 2020, just 1,200 Haredim was serving in the IDF.

Now twice that number have volunteered to fight over the past two weeks.

Rabbi Ravad did his Torah study as a teenager and then decided to continue to military service.

He later served as chief rabbi to Israel's Air Force.

When the IDF needed recruitment help after the October 7 Hamas attacks, they knew who to call.

RABBI RAMI RAVAD, Former Israeli Defense Forces Officer (through translator): The army told me, if you bring 50, we will open a unit.

They asked for 50.

I brought 450.

I now have a list of 1,400 Haredis who are interested in joining to help the army in these horrible days.

LEILA MOLANA-ALLEN: Ravad hopes this new call to serve amongst young Haredim will change his community's relationship with Israeli society.

RABBI RAMI RAVAD (through translator): There's a problem in this country that Israel's public doesn't understand the ideology of the Ultra-Orthodox.

And that's why the subject creates a lot of conflict.

There are some who interpret their beliefs as the Haredi community being against the army.

LEILA MOLANA-ALLEN: He says the influx of volunteers is proof that simply isn't true; 30-year-old father of three Moti Leitner is one of those volunteers.

Raising his family in the Ultra-Orthodox neighborhood of Bet Shemesh, he never saw army service in his future.

The terror attacks changed his mind.

MOTI LEITNER, Israeli Defense Forces Volunteer: We saw since and picture and movies that only -- you know it, you hear it only from the movie.

And it's real, babies and adults and teenagers, terrible things.

And, actually, I sit here and cry, cry and cry and cry.

I couldn't sit and just do nothing.

LEILA MOLANA-ALLEN: Moti knows joining up will transform the quiet life he and his wife Ayala (ph) have built for themselves here.

MOTI LEITNER: I have my wife's support.

So that's what is -- that's what I need, actually.

She will pay the price of my decision.

But she's OK with that.

LEILA MOLANA-ALLEN: As for training and deployment, he knows he will be miles behind those who were put through their paces at 18, but says he's up for the challenge.

Moti, most of the people who are being called up have done their military service, however long ago it was.

You have never been trained.

You have never fought before.

Are you afraid?

MOTI LEITNER: We don't have a choice.

We should be there and do our best.

LEILA MOLANA-ALLEN: Moti realizes many who share his beliefs aren't ready to take the same step.

But he hopes they will soon see a new belief the attacks have given him, that, to keep their community safe, they must do that physical, as well as religious part.

MOTI LEITNER: What it was in the past will not be in the future.

Everything will be -- we're going to change.

LEILA MOLANA-ALLEN: As Israelis unite across political and religious divides for the war effort, the question remains whether this fight will change society for good or simply kick internal disputes on down the road.

For the "PBS NewsHour," I'm Leila Molana-Allen in Jerusalem.