Pope Francis exchanges gifts with the Egyptian imam of al-Azhar Mosque, Ahmed Mohamed el-Tayeb, during a private audience at the Vatican on May 23. (Getty Images)

With a hugely symbolic hug and an exchange of kisses on the cheek, Pope Francis and the grand imam of Cairo's al-Azhar Mosque, which houses a 1,000-year-old university, took a major step toward restoring relations between major branches of the world's two largest faiths, Roman Catholicism and Sunni Islam. The two met privately for 25 minutes in the pope's private library at the Vatican.

"This meeting is the message," the pope told the imam, Ahmed Mohamed el-Tayeb.

More than five years had passed since comments made by the previous pope, Benedict XVI, put religious authorities at al-Azhar on the defensive, and relations on ice. After a Christmas Eve bombing of a Coptic Christian church killed 21 people in 2010, Benedict said the attack was "yet another sign of the urgent need for the governments of the region to adopt effective measures for the protection of religious minorities."

Tayeb, who remains al-Azhar's grand imam, had found Benedict's statement insulting. A religious council under his direction “reviewed in an emergency meeting ... the repeatedly insulting remarks issued by the Vatican Pope towards Islam and his statement that Muslims are discriminating against others who live with them in the Middle East,” according to a written statement from January 2011. “The council decided to freeze dialogue between al-Azhar and the Vatican for an indefinite period."

Cairo also recalled its envoy to the Vatican at the time. Coptic Christians, who have their own pope based in Alexandria, make up more than 10 percent of Egypt's population. "Egypt will not allow any non-Egyptian faction to interfere in its internal affairs under any pretext," the Foreign Ministry said in 2011. "The Coptic question is specifically an internal Egyptian affair."

Tayeb saw Benedict's comments as explicitly linking Islam with violence, while also ignoring the killing of Muslims at a time of great bloodshed throughout the region. "I disagree with the pope's view, and I ask why did the pope not call for the protection of Muslims when they were subjected to killings in Iraq?" he asked at the time.

Before Benedict's comments, al-Azhar's relationship with the Vatican had been at its best in centuries. Pope John Paul II, Benedict XVI's predecessor, visited the mosque and university in Cairo in 2000, capping years of concerted dialogue between the two institutions.

Al-Azhar is the center of Islamic study for Sunni Muslims, who account for about 85 percent of the Muslim world, and its scholars occasionally issue religious edicts that have included denunciations of radical Islamists and violence. In 2009, al-Azhar was a co-host of President Obama's landmark address to the Islamic world at Cairo University.

Christianity has an estimated 2.2 billion adherents worldwide, with Catholics accounting for the majority of them. Roughly 1.6 billion people around the world are followers of Islam.

Francis has made numerous overtures to religious harmony, and has dedicated particular sympathy toward the plight of Muslim refugees fleeing wars across the Middle East — while also raising concern about persecution of Christian minorities. He has repeatedly called for tolerance of Muslims at a time when anti-Muslim sentiment is gaining political momentum across Europe. When Sadiq Khan became London's first Muslim mayor, Francis congratulated him and hailed him as a beacon of tolerance.

Mahmoud Azab, an adviser of Tayeb's, told Catholic News Service that Francis reached out to al-Azhar soon after being elected pontiff in 2013. "It was magnificent. We got a letter signed by the new pope," Azab said. "His Holiness said, 'I put a lot of importance on working together to realize a good understanding among our people.'"

Sectarian violence against Coptic Christians has diminished since Mohamed Morsi's Muslim Brotherhood-led government was toppled in 2013. Copts feared that an Islamist government would ignore the continued persecution. Morsi's unseating was jointly engineered by the current Egyptian leader and former defense minister, Abdel Fattah al-Sissi, the current Coptic pope, Tawadros II, and Tayeb of al-Azhar.

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