Pope Francis met with Iraq’s most influential Shiite Muslim leader, Grand Ayatollah Ali al-Sistani, on a Saturday in a historic encounter aimed at building bridges between Christians and Muslims.

The two leaders invoked religion for the cause of peace and protection of the vulnerable, including Iraq’s beleaguered Christian minority. The summit at al-Sistani’s residence in the city of Najaf was the first-ever meeting between a Catholic pope and a Shiite grand ayatollah in Iraq.

In a statement issued by his office afterward, al-Sistani affirmed that Christians should “live like all Iraqis, in security and peace and with full constitutional rights.”

Al-Sistani wished Francis and the followers of the Catholic Church happiness and thanked him for taking the trouble to visit him in Najaf, the statement said.

Pope Francis, who on Friday called on Iraq’s political leaders to guarantee the equal rights of the country’s Christians, thanked Mr. Sistani “for speaking up—together with the Shiite community—in defense of those most vulnerable and persecuted amid the violence and great hardships of recent years,” the Vatican said.

Iraqis cheered the meeting, and the prime minister responded to it by declaring March 6 a National Day of Tolerance and Coexistence in Iraq.