With its red-brick spire and stained-glass windows, St Johannes looks like any other 19th-Century Protestant church.
Go around the back, however, head up a few flights of stairs and you come to a simple white room, with shoes neatly laid out at the entrance and patterned prayer rugs folded away in a corner. That is because this is a mosque.
The room is being rented from the parish, while the church remains active.
But the mosque is not unusual because of its location. Rather, because of the people who come here. At Berlin's newest mosque, men and women pray together, women are allowed to lead Friday prayers, and gay, lesbian and transgender people are welcome.
"Our mosque is open for everybody," says mosque founder Seyran Ates, a German Turkish-born lawyer and women's rights activist.
"And we mean that really seriously: everybody, every lifestyle. We are not God. We don't decide who's a good or a bad Muslim. Anybody can come through this door - whether you are heterosexual or homosexual, we don't care, it's not our right to ask."
The Ibn Rushd-Goethe mosque is part of a growing movement known as inclusive Islam.
There are now liberal Muslim communities and inclusive mosques all over the world - some in private homes, others in changing locations - but Ms Ates says the Berlin mosque is a major step forward for inclusive Islam, because it is the first permanent liberal mosque, with a sign on the door, open to anyone.
"What we did new, is that this is a fixed place. And it's not a place where only people come who know each other. It's not a closed club. We are open. We tell everybody, here is a place you can come to."
One of the first inclusive mosques was set up in Paris in 2012 by Ludovic-Mohamed Zahed, a gay imam from Algeria who now lives in France with his male civil partner. He is working with Ms Ates to help set up inclusive mosques elsewhere, including in Britain.
"Europe is the place where we can work on, what we consider to be, the reform of Islam," he tells me during a visit to the new mosque in Berlin.
"Because we have freedom of speech and democracy and education and welfare."
I ask him what he would say to Muslims who believe that homosexuality is a sin.
"To those who are Muslim and believe you can't be gay or an emancipated woman at the same time as being Muslim, I would say: you can't be homophobic, misogynistic, Judeophobic and pretend to be Muslim," he replies.
"Because Islam means being at peace with yourself and others. So that would be an oxymoron, it would be a contradiction."
'A new thing for me'
The mosque is controversial. Ms Ates has received hundreds of death threats from extremists, mainly from Turkey and the Arab world. Some were sparked by a fake news report on Turkish TV, showing pictures of the Koran being trodden on in her mosque. In fact, she says, the Koran was thrown on the floor and stepped on by the Turkish journalists who came to the mosque to film the report.
She has also received threats because of accusations from Turkish officials that she supports Islamic preacher Fethullah Gulen, who is accused by Turkish President Recep Tayyip Erdogan of staging last year's failed coup in Turkey.
As a result of these threats, the police protection she was already living under has been stepped up.
The Turkish religious authority Diyanet and Egyptian officials have said that what is practised in the mosque is "not Islamic." Even some Muslims who condemn the death threats do not necessarily agree with her.
Opa, a Muslim visiting Germany from Gambia, admits he struggles with the idea of men and women worshipping together. Mixed prayers could be distracting for worshippers, he says.
"I was surprised when they told me, that men and women join together and they pray, because normally men are in front, the women are behind. They have a barrier, so they can't see each other," he says. "This is a new thing for me."
'Why should I judge?'
Inside the mosque I meet Miriam, who is leading a study group on how to recite the Koran. She patiently explains the correct pronunciation of the verses to Laqa, a man from Pakistan who has lived in Berlin for 28 years.
She tells me that the main point of the mosque is tolerance of each other's view of Islam. I ask her whether she has different views to those of Ms Ates.
"That's an easy one," she laughs, pointing to her head.
"I wear the headscarf and she interprets that in a different way, but she says she doesn't want a 'Seyran Ates mosque'. She wants a mosque for everyone. Actually I don't want to cling to names, like liberal or conservative. It's about tolerance, and tolerance is very deep in my religion."
This is the origin of our religion, adds Laqa. "We are all equal, whatever you look like, or whatever colour skin you have, whether you're gay or lesbian," he says. "I can't know whether they have a better connection to God than me. Why should I judge that? I can't. I shouldn't."
It is clear that this mosque is about much more than debates on liberal versus conservative, or whether women should wear headscarves or not. For Ms Ates it is about a revolution in Islam.
"That conservatives and orthodox accept us, as we have to accept them; that we can come together in peace; that all of kinds of Islam accept each other - that's my dream," she says.