Here some quotes from the report Syrian Jihadism by the Swedish Institute for International Affairs. The report is 46 pages, so this is just an impression.
As Fabrice Balanche has documented, major military conflict is limited to Sunni Arab areas only, while territories inhabited by religious minorities (such as Alawites, Druze or Christians) have by and large remained passively or actively supportive of the regime (Balanche 2011). [page 7]
The following fragment discusses the fact that more deaths are registered in Sunni areas. It is interesting because this is the province where the rebels claim to just have conquered a border post and are trying to infiltrate: The only real outlier in terms of religious demography and casualty numbers is the Raqqa Governorate in north-central Syria. Its more than 800,000 inhabitants are mostly Sunni Arabs, but the number VDC-counted deaths stood at only 73 on August 7, 2012. Different hypotheses may be advanced for this, including the tribal nature of the area, the low population density in the countryside, pro-government attitudes in some recently constructed communities (in conjunction with the Tabqa Dam project on the Euphrates), etc, but the Raqqa case clearly merits further study. [note page 7/8]
The non-armed opposition both inside and outside Syria retains some high-profile activists from a religious minority background, many of them formerly leading figures within the secular, pre-revolutionary dissident movement (including Alawites like Abdelaziz el-Khayyer or Aref Dalila, and Christians like Georges Sabra or Michel Kilo). However, this “political” opposition is by now marginalized by the military confrontation.
Virtually all members of the armed insurgent groups, regardless of their ideological inclination, are Sunni Arabs. They hail mostly from agricultural regions and provincial towns, which have suffered economically from Bashar el-Assad’s reform program. Major cities and middle-class areas have mostly remained quiet, but the insurgency now has a firm foothold in the ”poverty belt” of ramshackle suburbs ringing both Aleppo and Damascus, after decades of in-migration from deteriorating conditions in the countryside. [page 9]
The insurgent movement comprises some tens of thousands of fighters. It is organizationally split among hundreds of autonomous units, generally called ”brigades” (katiba, pl. kataeb), regardless of their actual size. [..] They are generally ”gathered along village or extended family lines, with little ideological content”. Fighters tend to be ”conservative and practicing Muslims” but organized and ideologically conscious Islamists form only a small minority (Jaulmes 2012).4 Even so, most fighters are acutely aware of their Sunni Muslim identity, and over time, the insurgent movement has taken on a Sunni sectarian hue. [page 9]
Nir Rosen, an American journalist who has travelled extensively among the Syrian rebels, points out that many insurgents ”were not religious before the uprising, but now pray and are inspired by Islam, which gives them a creed and a discourse.”(Rosen 2012a).[page 10]
A 1979-1982 uprising against Hafez el-Assad also began in a wave of broad civil protest against tyranny and a faltering economy, but was quickly sidetracked into violent sectarian conflict. [page 11]
The opposing side is not only a secular tyranny, but also identified with a ”heretical” religious group, the Alawites – or ”Noseiris”, as jihadis prefer to call them, using an older, denigrating term. Most Sunni theologians agree that Alawites cannot be accepted as Muslims, and the stricter salafi interpretations, which rely on old fatwas by the medieval scholar Ibn Taimiya, call for their expulsion or even extermination. Last but not least, el-Sham (a word which can mean both Damascus and the Levant or Greater Syria) plays an important role in Muslim eschatology, as a battlefield near the end of days.[page 11]
There are also a number of FSA Military Councils (Majalis Askariya) inside the country, currently nine. The councils generally represent the single strongest coalition of insurgent groups in their home areas, but this varies considerably from province to province. According to a source sympathetic to the Military Councils, they collectively gather some 50-60 percent of the total number of fighters identifying as “FSA” (excluding a significant minority of rebels who do not use the FSA label at all). [page 12]
“If you ask any of the nine Military Council commanders, they will tell you they have no general commander”, explains Brian Sayers, director of government relations for the Syrian Support Group, an American organization which provides funds and training to the FSA Military Councils.
In March 2012, five Military Councils jointly announced the creation of a new “internal” FSA leadership, appointing the Homs Military Council commander Col. Qasem Saadeddine as their top commander. Many viewed this as a move intended to displace Col. Asaad’s ineffectual exile leadership. Months later, the joint command does not appear to function well, if at all. Col. Saadeddine continues to appear in the media under this title, but his influence does not seem to extend beyond his own Homs Military Council. [page 13]
While attempting to build up the SNC-FSA alliance as the centrepiece of the Syrian opposition, these same states have also tried to hamper the development of rival, non-state Islamic donor channels. In May 2012, a number of Saudi religious scholars were ordered to stop collecting funds privately, and instead direct their followers to officially sanctioned aid agencies. A salafi-led aid group known as the Ulema Committee to Support Syria was forced to shut down its activity. [page 17/18]
High-ranking members of the Saudi religious establishment have since decreed that it is unlawful for Saudis to finance or fight in the Syrian jihad on their own initiative. According to Ali bin Abbas al-Hakami and Abdullah bin Mohammed al-Mutlaq of the Senior Ulema Commission, ”the FSA is responsible for the fighting and jihad in Syria, and should be supported”, but only through official channels set up by the Saudi government. Other states have issued similar rulings via the mosques, to stem the flow of volunteers and money to Syrian extremist groups ('Tunisian spokesman calls on preachers to stop pushing jihad in Syria among the youth'.)
However, private donations keep trickling into Syria, and the insurgents remain heavily reliant on informal methods of transfer. For example, a financing network run on behalf of the Syrian salafi theologian Mohammed Surour Zeinelabidin (funded mainly by Gulf donors) appears to be active in supporting both humanitarian and paramilitary Islamist groups, primarily in southern Syria. Islamic organizations and expat Syrian financiers continue to be a favored source of support even for non-ideological rebel commanders, due to the minimal red tape and corruption, and their proven track record of getting money into Syria. [page 18]
In an interview with Time Magazine, a member of the jihadi Ahrar el-Sham Brigades noted the inefficiency of the FSA’s state support in contrast to their own privately funded religious channels, saying that FSA members “get more support than we do, but our support is delivered to us, theirs doesn’t make it to them. [...] Their support stays in Turkey, it doesn’t make it to the revolutionaries here. If our supporters send us 100 lira, we get 100 lira.” [page 20]
Two groups in particular have been identified with the foreign fighter phenomenon: Jabhat el-Nosra and the Ahrar el-Sham Brigades. Both are among the most extreme salafi groups in the Syrian rebel movement, and Jabhat el-Nosra in particular is closely tied to the transnational jihadi environment. When asked by an el-Hayat reporter, an FSA commander in the Hama countryside singled out these two groups for using foreign fighters, claiming however that they comprise less than 20 percent of the manpower in Jabhat el-Nosra and less than 5 percent in Ahrar el-Sham. [page 21]
About the Jabhat el-Nosra group (believed to be closest to Al Qaeda): The same source adds that Jabhat el-Nosra freely receives non-Syrian volunteers, and that although the foreigners rarely participate in battles, they carry out the majority of suicide operations and conduct training for local members. However, the source also claims that some members of Jabhat el-Nosra are known to him for collaborating with the Assad regime during the Iraq war, and states that he believes that the group is “indirectly” manipulated by the regime. [page 26]
The second half of the report discusses a number of rebel organizations with some jihadist sympathies.