Inside the red-brick building that now houses the German capital's newest and perhaps most unusual mosque, Seyran Ates is staging a feminist revolution of the Muslim faith.

"Allahu akbar," chanted a female voice, uttering the Arabic expression "God is great," as a woman with two-toned hair issued the Muslim call to prayer. In another major break with tradition, men and women - typically segregated during worship - heeded the call by sitting side by side on the carpeted floor.

Ates, a self-proclaimed Muslim feminist and founder of the new mosque, then stepped onto the cream-colored carpet and delivered a stirring sermon. Two imams - a woman and a man - later took turns leading the Friday prayers in Arabic. The service ended with the congregation joining two visiting rabbis in singing a Hebrew song of friendship.

And just like that, the inaugural Friday prayers at Berlin's Ibn Rushd-Goethe Mosque came to a close - offering a different vision of Islam on a continent that is locked in a bitter culture war over how and whether to welcome the faith. Toxic ills like radicalization, Ates and her supporters argue, have a potentially easy fix: the introduction of a more progressive, even feminist brand of the faith.

"The intention is to give liberal Islam a sacred space," Ates said. "I feel very discriminated by regular mosques where women have to pray in ugly backrooms."

The subject of withering criticism as well as hopeful support, the house of worship is part of a small but growing number of liberal mosques founded all or in part by women. Seen by their backers as an antidote to gender bias that often leaves Muslim women praying in smaller spaces, the new kind of "feminist mosques" amount to a rallying cry for change, observers say.

In London, for instance, the female-founded Inclusive Mosque Initiative opened its doors in 2012. Female imams routinely lead prayers in spaces that welcome male and female Muslims of any sect - gays and lesbians included. More recently, mixed-gender or all-female prayers have spread to boutique mosques from California to Switzerland to Denmark.

Women and men traditionally pray separately in mosques for reasons of modesty. Some argue that the Koran does not explicitly call for separation, but others say that female voices should not be heard during prayer.

Nevertheless, women are said to have served as imams in ancient Islam, and female Muslim activists have been challenging the norms surrounding the religion for decades. Notable among these activists is Amina Wadud, an American who famously delivered a Friday sermon at a South African mosque in 1994.

Enter Ates, who opened the Berlin mosque largely through donations. A 54-year-old Turkish Kurd, she is both well known and polarizing in Germany's Muslim community of more than 4 million. As a student, she narrowly survived a gun attack at a counseling center for Turkish women. And after years of fighting for women's rights, repeated death threats forced her to close her legal practice in 2006.

The debut of her mosque brought a round of fire on social media from critics. "#Mosque without #Islam. Those who know Ates know that she is in favor of an Islam that is not based on its sources," tweeted the advocacy group Generation Islam.

Burhan Kesici, chairman of the Islamic Council for the Federal Republic of Germany, dismissed her house of worship as a fad.

"We're observing this and are wondering . . . how what is happening there is supposed to be rooted in Islam at all," he said.

He added, "Of course women are equal. That there's a separation in religious practice doesn't mean that they're not equal. I'm curious how long this congregation will last. . . . It seems a random conglomerate of different Islam critics."

At the inaugural service Friday, the mosque housed inside an old theater space of a Protestant church lured more journalists than worshipers, as well as a significant security presence. Among the young Muslims attending was Haithm al-Kubati, 26, a Yemeni who moved to Germany six years ago.

It was, he said, his first time praying in a mosque with women.

"It still takes a bit of getting used to. But it's often the case when something is new that it is a bit strange, perhaps even a bit scary. But I am sure that this is the way of the future," he said.

Elham Manea, the female imam who shared in leading the Friday prayers, said mixed worship is an issue of equality.

"How and when a woman is asked to pray mirrors her social status within her community," Manea said. "She is asked to pray separately from men, to cover her hair during prayer . . . and to stop praying during the days of her menstruation. . . . All these restrictions are imposed on her because they mirror the social conviction that a woman is not fully complete and perfect like a man and [that] she without doubt isn't equal."

"I understand that change is hard, because one is used to doing the same thing for centuries, and it will of course be difficult to change it. But still the time for change is now. . . . And we're calling for it respectfully."