BEIRUT — The 29-year-old Syrian rebel is full of enthusiasm as he prepares to return to the battle front after nursing his leg wound, his second this year, in a northern Lebanese city.

A jovial young man with a long bushy beard, he discusses the war the rebels are now waging with one eye shifting to the television screen to keep track of the archery competition at the Olympics, though he says his favorite sport is rifle shooting.

He is tracking the rebels’ progress in the northern city of Aleppo and says he plans to join the battle for the capital, Damascus. “We have optimism, we have persistence and we have high morale,” says the man, who goes by the name of Abu Berri.

Syria’s rebels are also driven by religion in their now 17-month-long campaign to bring down President Bashar al-Assad, first through peaceful protests and more recently through a military struggle. Abu Berri says he became a committed member of the Salafists, the ultraconservative Sunni sect, after spending nine years in Saudi Arabia.

Many of his peers, he says, are also becoming Salafists, even those who have little understanding of this brand of puritanical Islam. Abdelr Razzaq Tlass, the charismatic leader of a brigade in the city of Homs, traded his mustache for a beard, he notes. “They grow beards to defy the regime,” he says. “In fact, we’re even willing to say we’re al-Qaeda to annoy the regime.”

Syrian activists often play down the religious aspect of the country’s revolution, insisting that in a conservative society it is only natural that people who are suffering should seek refuge in religion. But as the regime’s brutality has intensified, the rebel movement has become more radicalized. In this overwhelmingly Sunni Muslim struggle against a minority Alawite regime, Salafists and other Islamists say they are fighting a jihad against the Assads.

To the alarm of Western governments cheering for the rebels, a fractured movement has also been joined by a still limited but apparently growing number of fighters from other Arab and Muslim states, including Iraqis who belong to al-Qaeda.

Reports of the black flag of al-Qaeda flying in parts of Syria, along with the recent kidnapping of two Western journalists near the Turkish border by an Islamist gang that seems to have included many foreigners, have led to fears that Syria is becoming a magnet for global jihadists.

One spokesman for the Free Syrian Army says four or five groups of foreign fighters are now operating in the northern province of Idlib, most of which the regime no longer controls. Some of them are accepted, even if not warmly welcomed, because they bring funds and military expertise.

Analysts say that distinctions have to be made — between Syrian Islamist fighters and non-Syrians, and even among the various foreigners.

Syrian Salafists who took up arms, they note, should not be assumed to be al-Qaeda-type jihadists, who hold the extremist belief that all those not with them are infidels, whatever their religion. An activist who works with the Free Syrian Army in Idlib says that rebels are suspicious of the Nusra Front, which has claimed responsibility for a string of suicide bomb attacks. But he says the Free Syrian Army is cooperating with groups such as Ahrar al-Sham, one of the main Salafist coalitions in Damascus, with affiliates in other provinces, and Liwaa al-Tawhid, an Islamist coalition of groups fighting in Aleppo.