TIRANA, Albania (AP) — Pope Francis denounced that extremists around the world are "perverting" religion to justify violence as he arrived Sunday in Albania, a Balkan nation where Christians and Muslims endured brutal religious oppression under communism but today live and work together peacefully.

Security was unusually tight for Francis' visit to the majority Muslim country amid reports that militants who trained in Iraq and Syria had returned and might pose a threat.

The Vatican insisted no special security measures were taken, but Francis' interactions with the crowd were much reduced compared to his previous foreign trips: His open-topped vehicle sped down Tirana's main boulevard, not stopping once for Francis to greet the faithful as is his norm.

He only kissed a few babies at the very end of the route as he neared the square where he celebrated Mass. Uniformed Albanian police formed human chains to keep the crowds at bay behind barricades while Francis' own bodyguards stood watch, perched on the back of his car or jogging alongside. Albania's Interior Ministry promised "maximum" protection from 2,500 police forces and beefed-up patrols at border crossings.

In his opening speech, Francis told President Bujar Nishani, Albanian officials and the diplomatic corps that Albania's interreligious harmony was an "inspiring example" for the world, showing that Christian-Muslim coexistence was not only possible but beneficial for a country's development.

"This is especially the case in these times in which authentic religious spirit is being perverted by extremist groups, and where religious differences are being distorted and instrumentalized," he said.

"Let no one consider themselves to be the 'armor' of God while planning and carrying out acts of violence and oppression!" Francis said in the wood-paneled reception room of Tirana's presidential palace.

That harmony was on hand during Francis' main event Sunday: A Mass in a square named after Albania's most famous Catholic — Mother Teresa — attended by tens of thousands of people, including senior representatives of Albania's Muslim, Orthodox and Bektashi groups, seated in places of honor.

It was Francis' first visit to a majority Muslim nation since the Islamic State crackdown on Christians in Iraq, with members of religious minorities being killed, persecuted or forced to flee their homes by militants. The Vatican has voiced mounting concern about the exodus of faithful from lands where Christian communities have existed for 2,000 years.

Muslims make up about 59 percent of Albania's population, with Catholics amounting to 10 percent and Orthodox Christians just under that, according to the country's official figures.

Francis' decision to visit tiny, poor Albania before any major European capital is in keeping with his desire for the Catholic Church to go to the "periphery." Albania is seeking European Union membership and his visit comes just a few weeks before he delivers a major speech to the European Parliament in Strasbourg, France.

Albania's president, Nishani, thanked Francis for making the country his first European destination, saying it was a historic event for all Albanians.

"There is no intolerance, extremism among us but reciprocal respect inherited from generation to generation," he said. "From an atheist country, we have turned into a country of religious freedom."

The capital's main Boulevard Martyrs of the Nation was decorated with Albanian and Vatican flags, as well as giant portraits of 40 Catholic priests who were persecuted or executed under Stalinist dictator Enver Hoxha, who declared Albania the world's first atheist state in 1967. Hundreds of priests and imams were jailed, scores executed before the regime fell in 1990.

Francis paid tribute to these martyrs and those from other faiths, saying they showed witness to their faith even under persecution.

"Recalling the decades of atrocious suffering and harsh persecutions against Catholics, Orthodox and Muslims, we can say that Albania was a land of martyrs," he said in his homily. Deviating from his text, Francis thanked Albanians for their ancestors' sacrifice, recalling the national symbol of the eagle.

"Do not forget your wounds, but don't avenge them," he said. "Go forward, flying on the hopes of a great future."

Francis has a busy schedule in Tirana: In addition to the address to Albanian authorities and Mass, he was meeting with leaders of different faiths, celebrating a vespers service and visiting children cared for by charitable groups.

Albanian police said they had the security situation under control. Cell phone providers complied with a request from police to jam cellphone reception in the area where the pope was in downtown Tirana. People attending the pope's Mass were told to avoid wearing heavy clothing since they would be checked by police and not to bring bags, suitcases or glass bottles.

"There is no threat to the pope's security. We have undertaken all the measures and everything will go well," police chief Artan Didi told reporters after a meeting with Interior Minister Saimir Tahiri on final security arrangements.

While the Vatican maintained no special security measures were being taken in Albania, security at the Vatican itself has been beefed-up in recent days: More barricades and police were out in force during Francis' weekly general audience this past week and Italian media reported security was being doubled.

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Winfield contributed from Rome. Trisha Thomas contributed from Tirana.