Pope Benedict appealed on Friday for a halt to the flow of arms into Syria, saying it would help end a civil war which has killed many thousands of people and which Christians fear could bring Islamists to power.
In his strongest comments yet on the conflict, Benedict branded the weapons imports as a "grave sin" as he arrived at the start of a three-day visit to Beirut, just 50 km (30 miles) from the Syrian border.
He also described Arab uprisings as a positive "cry for freedom" as long as they included religious tolerance - the central theme of Benedict's trip which is focused on promoting peace in the Middle East and harmony between its minority Christians and majority Muslims.
Christian, Sunni and Shi'ite Muslim and Druze religious leaders joined Lebanon's political elite in greeting Benedict on his arrival in a region rocked by protests against a U.S.-made anti-Islam film.
"The import of weapons has to finally stop," Benedict, 85, told journalists on the plane. "Without the import of arms the war cannot continue. Instead of importing weapons, which is a grave sin, we have to import ideas of peace and creativity."
The Arab Spring uprisings against authoritarian leaders were "a positive thing. There is a desire for more democracy, more freedoms, more cooperation and renewal," he said.
But he added that it had to include tolerance for other religions. Asked about Christians' fears about rising aggression from Islamist radicals, Benedict said: "Fundamentalism is always a falsification of religion."
All main faith groups in the country, which fought a civil war along sectarian lines from 1975 to 1990, have welcomed the visit. Among banners greeting Benedict on the road from the airport were several from the militant Shi'ite group Hezbollah.
PROTEST IN NORTH
Clashes from the Syrian war - an opposition group says more than 27,000 people have been killed in the uprising against President Bashar al-Assad - have occasionally spilled over into Lebanon, evoking fears of renewed strife.
Tensions have been rising between Lebanon's Sunni Muslims, who generally back the uprising led by Syria's Sunni majority, and Shi'ites who usually support Assad's minority Alawite sect, an offshoot of Shi'ite Islam.
In the mainly Sunni Muslim northern city of Tripoli one person was killed in clashes with security forces after Islamist protesters set fire to a U.S. fast food restaurant and tried to storm a government building. At least 14 people were wounded, most of them from the security forces.
Witnesses said the crowd chanted against the pope's visit and shouted anti-American slogans in protests over a film insulting the Prophet Mohammad. "We don't want the pope," and "No more insults (to Islam)" they chanted.
Benedict angered Muslims early in his papacy by suggesting in a 2006 lecture that Islam was violent and irrational. He said this was a misunderstanding and visits to Turkey later that year and Jordan in 2009 largely calmed the controversy.
More than 5,000 military and security personnel were being deployed to protect the pontiff, al-Nahar newspaper said. Beirut airport closed for two hours on his arrival and roads on his route through the capital were closed.
In Saint Paul's Basilica overlooking the Mediterranean Sea, Benedict appealed to religious leaders to do all they could to uproot the threat of fundamentalism which he said "indiscriminately and fatally affects believers of all religions".
The call came in a so-called "apostolic exhortation" to Middle Eastern Christians which the pope formally issued in a signing ceremony watched by Lebanese church leaders.
The document said the Middle East was suffering a "haemorrage of Christians who find themselves in a delicate position, at times without hope", Benedict asked political and religious leaders to avoid policies that would lead to a "monochromatic Middle East".
Christians have been steadily abandoning the birthplace of their faith in recent decades to escape wars, political unrest and discrimination by the region's majority Muslims.
Benedict's message resonated among the crowd who gathered outside, waving Lebanese and Vatican flags.
"We feel weak here. His visit is a time for us to feel proud, to give us strength in a challenging time for the region that of course has us Christians nervous," said Isabelle, a 35-year-old resident of Harissa where the service took place.
Christians now make up about 5 percent of the Middle Eastern population, down from 20 percent a century ago. If current pressures and their low birth rates continue, some estimates say their 12 million total could be halved by 2020.
About two-thirds of Lebanon's Christians are in full communion with the Vatican, either as members of the five local churches linked to Rome - the Maronites, the largest group, and the Greek Melkite, Armenian, Syriac and Chaldean Catholics - or of the worldwide Roman Catholic Church itself.
The rest belong to five Orthodox churches - the Greek, Armenian, Syriac, Assyrian and Coptic Orthodox - and small groups of Protestants, mostly Presbyterians and Anglicans.
Benedict will also hold two major open-air events and meet leaders of all Lebanon's many Christian and Islamic communities, as well as the country's political leaders.