If you follow the boisterous groups of cross bearers and prayer-humming nuns who weave through the narrow streets of Jerusalem’s Old City, you’ll eventually end up in a rare clearing that holds one of Christianity’s holiest buildings: the Church of the Holy Sepulchre. Orthodox and Catholic Christians consider the complex to be built on the site of the crucifixion, burial, and resurrection of Jesus Christ, and the ancient structure is like no church you’ve ever seen: a layered, winding complex of various tombs, relics, and caverns.

It’s also one of the most contentious sites in Christianity. Six Christian denominations—Greek Orthodox, Armenian Apostolic, Roman Catholic, Coptic Orthodox, Ethiopian Orthodox, and Syriac Orthodox—share jurisdiction of the cavernous church and have been notoriously unable to keep themselves from throwing punches at the slightest perceived offense. Warring factions can cause disastrous problems, so when the combative holy clerics threatened the protection of one of the religion’s holiest sites, there was only one way to keep the peace: find a neutral mediator.

Enter two Muslim men: Wajeeh Nuseibeh and Adeeb Joudeh. Since 1192, when a peace agreement was brokered, giving control of the front gates to Muslim gatekeepers, the ancestors of these two men have been the key holders and mediators for the sacred church. Each day since the accord, their families have opened the church to worshipers. The ritual begins around 4 a.m., when Joudeh delivers the cast-iron key to Nuseibeh, who unlocks the wooden doors to the church. When nightfall hits, the two reverse the ritual, locking it up for the night. The Muslim families have also been tasked with symbolic roles in holiday rituals, and they work as peacekeepers for the often-quarreling Christian sects.

Over the past centuries, the church has been the site of tense standoffs between rival factions. Any perceived encroachment, especially during holidays, has been known to erupt into fistfights, sometimes requiring police intervention. (You won’t believe this ridiculous video from 2008.)

The territorial sects have a history of shady hijinks that have kept them all continuously on edge. During Easter prayers in 1970, Coptic monks momentarily left their post on the rooftop monastery, which allowed the Ethiopian monks to swoop in, change the locks, and take it for their own. Since then, the Copts have protested by posting at least one monk outside the disputed area at all times. And in 2002, when that monk moved his chair into the shade, a dozen holy men were injured in the resulting brawl.

Moreover, sectarian tensions make repairs almost impossible to negotiate. Because of this rooftop disagreement, the crumbling structure, deemed “a danger to human life” by engineers, has been left in disrepair for years.

“Like all brothers, they sometimes have problems. We help them settle their disputes. We are the neutral people in the church. We are the United Nations. We help preserve peace in this holy place,” Nuseibeh told the San Francisco Chronicle in 2005.

Sometimes the contentions around jurisdiction reach almost comical levels. In 1995 the six denominations finally came to an agreement on painting a section of the central dome after 17 years of debate. And on an upper-floor window ledge, there’s a ladder that has been immobile since being placed there in the early 1800s. Afraid to incite violence and unsure which denomination has the right to the ladder, no one has moved it since.

It’s worth noting that the two Muslim families tasked with keeping the peace aren’t immune to arguments of their own—though nothing on the scale of the tensions beyond the church’s entrance. “Yes, we share the responsibility with the Joudehs, and sometimes we argue, as happens in a family,” Nuseibeh told the International Business Times earlier this year. He believes that his family was the first to hold the key and Joudeh’s came later. But the latter disagrees.

“My ancestor who was given the keys was a sheik, a highly respected person, who was not supposed to perform physical labor, such as climbing the ladder to open the gate,” Joudeh noted later in the article. “That’s why the Nuseibehs were called in to perform this duty. Unfortunately, they feel still ashamed of being just the doorkeepers.”

Nuseibeh disagrees. “It’s like having a million dollars and not being able to spend a single cent,” he said of the other man in an interview with The Philidelphia Inquirer.

Sounds like loving thy neighbor is easier preached than practiced.