On Monday, Recep Tayyip Erdoğan became the first Turkish president to visit the Vatican in 59 years. The trip marks a new high point in relations just three years after Turkey recalled its ambassador to the Holy See when Pope Francis acknowledged the Armenian genocide. Significantly, Erdoğan, rather than Pope Francis, initiated the meeting. He had called the Pope in December after President Donald Trump’s decision to move the US embassy in Israel from Tel Aviv to Jerusalem. According to Turkish officials, Erdoğan and Francis agreed to defend the international status quo on Jerusalem. Turkey has long seen itself as a defender of Muslim interests on the world stage. It believes the Vatican has a similar role in the Christian world. Hence Erdoğan’s desire to be photographed next to Francis beneath headlines proclaiming their agreement on Jerusalem. The message: Muslims and Christians are united against the change. The Turkish president was hoping for one more favour: a papal condemnation of what he described, as he left Istanbul for Rome, as “rising Islamophobia in the West”. The Pope was no doubt happy to oblige: he has taken great care not to identify Islam with violence, even when honouring victims of jihad such as Fr Jacques Hamel. What does the Holy See receive in return for Erdoğan’s visit? It underlines its role as an interlocutor between the West and Muslims worldwide. But beyond that, it gains a new opportunity to speak up for Turkey’s embattled Christian minority. Christians make up just 0.2 per cent of the country’s 80 million population. Conversion from Islam to Christianity is illegal. The state has frequently confiscated Church property. And according to the country’s Association of Protestant Churches, hate speech and hate crimes against Christians are rising. Pope Francis is likely to have raised these matters quite bluntly with Erdoğan. He did so back in 2014, when he became the first head of state to visit the newly built presidential complex in Ankara (its centrepiece is a £500 million mansion with 1,050 rooms). Francis is especially concerned about the Turkish government’s attitude towards the Ecumenical Patriarch of Constantinople, Bartholomew I. The spiritual leader of the world’s 300 million Orthodox Christians, and arguably the Pope’s closest ecumenical ally, lives in the Fener district of Istanbul, the historic centre of Eastern Christianity. To shore up his precarious position within Turkey, he recently signed a document endorsing the country’s offensive in northern Syria. Pope Francis surely hopes he can influence Erdoğan to ease at least some of the pressure on Patriarch Bartholomew. Are there any downsides to the Holy See’s rapprochement with Turkey? The Vatican risks alienating the Trump administration by condemning its decision on Jerusalem so publicly. But this gesture is likely to be shrugged off at the White House, where officials are well aware of the vast policy differences with the Holy See on everything from the environment to immigration. It won’t make the Trump-Francis relationship any easier, but it won’t destroy it either.