Cantor Anita Thornton helps lead the Kol Nidre service, which marks the start of Yom Kippur, Friday at George Mason High School in Falls Church, Va. (Eva Russo/For The Washington Post)

The first time Sam Simon saw a screen used to project prayers during Sabbath services, “it took my breath away.” And not in the good sense.

“It feels intrusive, disruptive on Shabbat,” the 68-year-old McLean techie said of his experience in a D.C. synagogue, using the Hebrew word for Sabbath.

Only the most traditional interpret Judaism’s prohibition on working, or creating, on the Sabbath as prohibiting the turning on of electricity and electronics, encompassing such activities as flicking a light switch, heating up the oven or driving a car between sundown Friday and sundown Saturday.

But the idea that technology in spirit can present a threat to this sacred commandment has permeated much of American synagogue culture, even for liberal Jews such as Simon. Many still consider the sight on Sabbath of a cellphone, tablet or a flashing screen disturbing when they come to services.

As a result, American synagogues have been cautious on technology. Meanwhile, much of institutional religion, hoping to lure back a wandering America, has been using technology to reach more people, experimenting with things like launching church DJs or holding services via Facebook.

But the digital revolution is now chipping away at a millennia-old barrier: The Jewish Sabbath.

Reform synagogues — a large, liberal part of Judaism — are expanding their use of technology on the Sabbath, experimenting carefully with live streaming serv­ices and projected images. The Conservative movement, long considered the middle road of institutional U.S. Judaism, had an intense back-and-forth this summer over a proposal to use e-readers to pray on the Sabbath. And while Orthodox Jewish leaders are unanimously opposed to turning any device on during the Sabbath, reports are being widely shared in the past year or so that huge numbers of young Orthodox send text messages, seeing it as socializing, not work. They call it “half-Shabbos” (Shabbos is the Yiddish word for Sabbath.)

The issue will be highlighted this weekend because of Yom Kippur, the holiest day on the Jewish calendar and one of the few times a year most U.S. Jews go to synagogue. Sabbath rules apply on Yom Kippur, which happens to fall this year on the Sabbath.

Beliefs and practices around technology and the Sabbath differ widely among U.S. Jews.

The Orthodox believe the process of electricity constitutes “creating” something and have systems of timers for things such as stoves and air conditioning, and avoid electronic doors and hotel key cards. Many ultra-Orthodox are opposed to use of the liberal Internet altogether and use “kosher phones” that don’t connect to the Web. Reform rabbis are fine with electricity and many have long used electrified musical instruments and screens to broadcast crowded services into overflow rooms, but have been hesitant on video cameras, e-readers or screens in the sanctuary. Conservative rabbis are somewhere in the middle, and are divided on much of this.

The questions are all new. Jewish law bans writing on the Sabbath, but are pixels — or the digital record of them — writing? If you type a search term into an iPad that holds scripture you’re using to pray, did you just write? Does downloading create a record the way writing does, even if you’re downloading some Talmudic analysis? If your community is on Facebook, are you connecting or disconnecting on the Sabbath if you post there?

For some the issue is simple: a desire to unplug. For others the concern is Jewish law, and how to interpret the ancient, detailed 39 categories of forbidden Sabbath work in our new, wired world. For others it’s cultural: Electronics just don’t mesh well at synagogue.

“It just doesn’t feel Shabbasdik,” Ethan Seidel, rabbi of the Conservative Northwest D.C. synagogue Tifereth Israel, said of projectors and screens, using a Yiddish adjective for the special, holy vibe of the Sabbath.

Seidel said screens are “intriguing” (though he doesn’t want to use them), he isn’t totally opposed to e-readers (as long as they’re not the wired ones you could use to surf the Web) and that he has structured some services like plays — so he’s open to experimenting. But he feels Jews should be wary before messing with the walls that have protected the Sabbath.

“I think there are a lot of people completely taken with technology and have lost their critical faculties,” Seidel said.

Conservative leaders had a dispute this summer when a prominent rabbi suggested using e-readers on the Sabbath during a convention of North American Jewish men’s clubs leaders — arguing that such devices are becoming the equivalent of books. The proposal was withdrawn.

A year earlier, the leader of the movement’s key rabbinical school wrote an 80-page opinion saying electronic devices violate the Sabbath because they create a record, which is too much like writing. Rabbi Danny Nevins’ opinion was approved by the Conservative Movement’s Committee on Jewish Law and Standards by a vote of 17 to 2.

Proponents of more experimentation counter with the obvious: The vast majority of Jews are already using the whole range of technology on the Sabbath. Judaism can’t be shut out of the digital revolution.

“Judaism is itself a technology. You name it — Torah study, mitz­vot, prayer, all these things are technologies that exist for you to connect more deeply with yourself, your community and God,” said Gil Steinlauf, rabbi of Adas Israel, a large Northwest Conservative synagogue currently reviewing its Sabbath electronics practices, from e-readers to live streaming video.

The cutting edge is at LabShul, a lay-led group that will host 1,000 people at a Tribeca arts center this weekend for Yom Kippur. The entire service will be, as it has been for seven years, projected on large screens. Images will include paintings of God by LabShul children, layered with verses of scripture. Pictures of stained glass windows will flash on the screens.

LabShul is led by Israeli-born actor and rabbinical student Amichai Lau-Lavie, whose uncle was the chief rabbi of Israel and who unplugs from calls and e-mails each Sabbath. He talks and writes about what prayer was like before the creation of books, before people’s hands and eyes were focused on the page.

“We have to be sophisticated consumers of technology, to see what violates our sacred space and time and what doesn’t,” he said this week. “I expect no less of Judaism at thousands of years old to come up with creative solutions, and it’s happening right now; we’re in the middle of it.”

In recent years, there have been groundbreaking digital translations of the Talmud, revolutionizing prayer for Orthodox Jews who need daily access to the Talmud’s 30-plus volumes. Using your device for non-Sabbath daily prayer is fast becoming so standard that sometimes people absentmindedly kiss their iPhones after praying — a ritual normally done with books.

Some Orthodox rabbis observe the “half-Shabbos” phenomenon and see something hugely important: The forming of a new Orthodox approach to technology. Others see run-of-the-mill rebellion.

Simon is someone who appreciates the importance of the Sabbath. He halts work and e-mail and spends the day at his synagogue, Temple Rodef Shalom in Falls Church. As a more progressive Jew, however, he believes Sabbath is more about your routines than what technology you use. He chuckles a little when recalling his jarring experience a few years ago at another synagogue.

“I’m a bit of a reluctant traveler, but I’m warming” to technology, he said.

Which is good, since Rodef Shalom leaders say they plan to experiment more with screens.