In a half-hour hearing at a functional court building in Ankara, a landmark step in the future of Istanbul’s 1,500-year-old Hagia Sophia was taken on Thursday. Although the decision of the Council of State’s 10th Chamber will not be known for up to two weeks, it could pave the way for the former cathedral and UNESCO World Heritage site to return to use as a mosque. Built by the Byzantines in the 6th century, Hagia Sophia was for centuries the world’s largest building, a centrepiece for Christianity and an engineering marvel. After conquering Istanbul in 1453, Ottoman Sultan Mehmet II made it a place of worship for Muslims. In 1934, Mustafa Kemal Ataturk’s secular regime turned it into a museum, a decision at the centre of Thursday’s hearing. The verdict has been highly anticipated since President Recep Tayyip Erdogan revived the debate in recent weeks. Before last year, Mr Erdogan remained outwardly ambivalent about Hagia Sophia but in the run-up to local elections he outlined his support for its role as a mosque. In May, he appeared on a giant screen as an imam recited the Quran from the iconic monument to mark the anniversary of the Ottoman conquest, an appearance that sparked an outpouring of support for re-designating the site. Such a move has been foreshadowed in other several cases since 2011 where museums that had been churches and later mosques, were reverted to mosques. “Given the latest push by Erdogan, who is now armed with legal precedents, Hagia Sophia’s conversion into a mosque is increasingly likely,” said Tugba Tanyeri Erdemir, of Turkey’s Association for the Protection of Cultural Heritage. “So far, the alluring prospect of converting Hagia Sophia has served Erdogan well to divert the attention of his voter base away from his political and economic failures. By the same token, Erdogan’s readiness to fire his one silver bullet by converting the Hagia Sophia to save the day is a clear sign of the severity of his current political predicaments.” As the court date approached, Christians around the world called for Turkey to back away from reclaiming the building, known as Aya Sofya in Turkish and one of the country’s leading tourist attractions, for Islam. The spiritual head of Orthodox Christianity, Istanbul-based Ecumenical Patriarch Bartholomew I, stressed its importance as a symbol of “mutual understanding and solidarity between Christianity and Islam.” He added that the change would “turn millions of Christians across the world against Islam.” Meanwhile, the Orthodox Church in Greece said a switch would “provoke strong protest and frustration among Christians worldwide” and Russian co-religionists warned it would “violate fragile inter-confessional balances.” US Secretary of State Mike Pompeo urged Turkey to retain Hagia Sophia’s museum status “as an exemplar of its commitment to respect the faith traditions and diverse history that contributed to the Republic of Turkey”. The Greek government also objected to any change, with Foreign Minister Nikos Dendias claiming it would be a “severe blow” to Turkey’s image. However, international intervention drew criticism from figures in Turkey’s ruling party. “We do not need anyone’s advice or recommendation on our own affairs,” said Numan Kurtulmus, the party’s vice-chair, while Foreign Minister Mevlut Cavusoglu also stressed it was a sovereign matter. “What is important is what the Turkish people want,” he said in a television interview.p In an open letter, dozens of academics raised concerns about the stewardship of the building. “Hagia Sophia is too beautiful a monument and too precious a historical document to serve as a pawn in regional politics,” they said. However, others said returning it to Muslim use would not detract from Hagia Sophia’s role for other religions or as a tourist attraction. “It used to be a mosque for centuries and the Ottoman state was a very tolerant state to religious minorities,” said Talha Kose, chair of political science and international relations at Istanbul’s Ibn Haldun University. “I don’t see any offence to other beliefs in this decision," Saygi Ozturk, a columnist for the secular Sozcu newspaper, said he expected the court to overturn the building’s museum status but that the decision would ultimately come from the government. “When we examine the previous decisions of the Council of State and the claims, it becomes clear that the re-transformation of Ayasofya into a mosque requires a political decision, not a legal one,” he said. Turkish media has speculated the multi-domed structure could open as a mosque on July 15 – the fourth anniversary of a coup attempt against Mr Erdogan. For the country’s tiny Christian minority, any change would mark a sad day for religious tolerance. “As a Turkish Christian I would like to see Hagia Sophia stay as a museum because I think that’s the best way to promote a message of peace and the principle of living together,” said Barkin Ozturk, a Catholic convert. “The decision has many political dimensions but I think the best thing would be to maintain the status quo.”