The Berlin worship center that poses a theological problem

Three religions. One roof. An unlikely trio of German men—a pastor, a rabbi, and an imam—began fundraising in June for the House of One, a joint church, synagogue, and mosque in the heart of Berlin. They hope to start construction by 2016.

The House of One will cost an estimated $58.3 million, a goal the team intends to meet through donations alone. Visitors to the project website can give money in units of “bricks,” €10 ($13.40) each. So far, people from around the world have paid for 3,500 bricks. Pastor Gregor Hohberg, Rabbi Tovia Ben-Chorin, and Imam Kadir Sanci all plan to practice their own faiths at the House of One, but also to demonstrate faith as a means for peace in a city of secular skeptics and in a world still suffering from religious violence.

“In the world we live in, we have two possibilities: war or peace,” Ben-Chorin said. “Peace is a process and in order to achieve it, you have to talk to each other.”

The House charter forbids using violence to settle differences and requires the three congregations to refrain from using the project as a way to convert followers from the other faiths. That could pose the biggest problem for the Christians, who are called to make disciples of all nations, not treat all faiths as equal. “The theological question is how the religions can maintain their claim of truth without disparaging the other religions,” Roland Stolte, 44, a House board member, told me.

Three separate service rooms will revolve around a common central area in the House design. A Berlin architecture firm, Kuehn Malvezzi, won the 2012 global competition to design the building and will top the structure’s middle tower with a green dome, nearly hidden from view by a cage of narrow brick pillars.

Jews will read the Book of Esther in their synagogue for the Purim feast but invite Christians, Muslims, and other curious guests to a dance in the common space afterward. Muslims will perform evening prayers in the mosque on Mohammed’s birthday but have seminars about him in the common space. Christians will celebrate Christmas in the church but teach others about Jesus in the common space.

The House construction site is Petriplatz, Berlin’s historic city center, where the churches of St. Peter stood from 1237 until 1964 during the Soviet occupation of East Germany. “The structure of the square was wiped out,” Stolte said. “In its place a concrete car park was created, and with that the square’s importance as the origin of the city, which was synonymous with religion, was buried.” City officials inherited the land in 1989 after the Berlin Wall fell. They already approved plans for the House.

“We might go towards a future without religion,” said Hohberg, who will continue to preach at St. Mary’s Lutheran Church even when the House is built. “Yet we are confident that this world will not be one without God or belief.”

But whose God, and whose belief? In what will be a tight-rope walk between respecting other people and treating all faiths as equal, the Christians will be faced with an important question: Is it really possible to profess Jesus Christ without encouraging your neighbors to do the same?

The Associated Press contributed to this report.