When the holiest days in the Jewish calendar begin Sunday at sundown, Jews worldwide will be praying for repentance and a good new year. For Reform Jews using a new High Holy Days prayer book, belief in God won't be required.

The Central Conference of American Rabbis has revamped the religious text used for a generation by the Reform movement — the most liberal arm of Judaism — for Rosh Hashanah, the Jewish New Year, and Yom Kippur, the Day of Atonement. Texts have been updated to be more feminist and gay-friendly, to acknowledge congregants with physical limitations and even to leave room for disbelief.

"One of the goals was to create a prayer book that was a prayer book for the 21st century, that is welcoming and inviting to everybody," said Rabbi Hara Person, the publisher of the new prayer book, "Mishkan HaNefesh."

In one example, a striking countertext to a prayer from Genesis ("The Lord God formed man from the dust of the earth … ") questions the scientific basis for the story of creation. It begins: "I speak these words, but I don't believe them."

"We wanted to allow for people who come in with doubt and anger, not to say there's only one way to approach these holidays," Person said. "There's a place for you regardless of who you are and what you're coming in with."

In the Twin Cities, Shir ­Tikvah in south Minneapolis has replaced its prayer books with "Mishkan HaNefesh."

"A prayer book is an interesting lens, a window into who a people is at a given moment," said Shir Tikvah's Rabbi Michael Adam Latz, who was involved in the early brainstorming of readings for the new book. Among his congregation, he said, "there is an enthusiasm and a sense that the last prayer book served us greatly for a generation, and now its time has passed."

The changes began with the design. Every two-page spread has what Person calls a "multi-screen" approach, reflecting modern digital devices. Every Hebrew prayer is matched with English transliteration — the sounds spelled out for those who cannot read Hebrew but want to sing or speak along. The translations on these pages have been updated, for instance, by referring to God as "she" or "compassionate mother" and replacing references to "bride and groom" with the non-gendered "couple."

For those who prefer to avoid the prayers altogether, there are alternate passages on the opposite page. Some are authored by rabbis, but others are by poets like Carl Sandburg, Pablo Neruda and Walt Whitman. Along the bottom are citations and scholarly elaborations on the texts.

That multi-screen approach is one way for Reform Judaism to reach a younger demographic, Person said. A 2013 study by the Pew Research Center found that Jewish millennials are more likely than Jews of older generations to identify themselves as having no religion (a finding consistent with other religions).

"We're appealing to the next generation by inviting them into the conversation," Person said.

Members can be themselves

Reform Judaism is the largest Jewish denomination in the United States, with one-third of U.S. Jews identifying with that movement, according to the Pew study. Other Pew findings: Intermarriage rates have been rising steadily over the past five decades, and U.S. Jews as a whole align with a largely left-of-center political ideology — other reasons to make religious services more welcoming to non-Jews and to politically liberal viewpoints, supporters of the changes argue.

"If you have people walk in the congregation and don't have to check some of the deepest parts of themselves at the door, but in fact the prayer book reflects that back and challenges us all to grow, that's remarkably holy," Latz said.

The Conservative Jewish movement also has revamped its holiday prayer book, publishing "Lev Shalem" in 2009. That book, too, offers contemporary translations of prayers with gender-neutral language and recognition of same-sex couples.

Other Reform synagogues in the metro area are considering adopting the new prayer book in the future.

Temple Israel, Minneapolis' largest Reform congregation, will use the old prayer book, "Gates of Repentance," but will pilot "Mishkan HaNefesh" in simultaneous small group services on the first nights of Rosh Hashanah and Yom Kippur. Eventually the congregation will switch over to the new books entirely, Rabbi Marcia Zimmerman said.

"Reform Judaism is about choice," she said. The new book "gives you all the traditional pieces so you can actually choose from the whole array, rather than the editors choosing for you, which is the heart of Reform Judaism. We loved that part of it."

Mount Zion Temple in St. Paul plans to move to the new books by next fall, said Executive Director Larry Solomon.

There was worry that some of the changes would generate a backlash, Person said, but so far, there hasn't been any. "That's not to say everybody likes everything that's in the book — not possible," she said.

The new prayer book is "not so dramatically different that it will be utterly alien to people," Latz said. Besides, he added, the High Holy Days are meant to be a little uncomfortable.

"The very themes of these Days of Awe are intended to unsettle us and stir us out of our complacency," he said. "Jewish worship is not intended to be a spiritual Jacuzzi."