Assad has been both the victim and the benefactor of religious ideology and organized religious mobilization. His staying or going has no impact on the motivations of the fighters on either side of the war because their wishes and aims are much higher and broader than the fate of his stupid regime.
They have been mobilized by their greedy clerics and imams to go to Syria to fight in what they believe is an exciting divine battle promised in the Koran, not to support or prevent a boring regime change operation orchestrated from the halls of the Pentagon and CIA headquarters.
An excerpt from, "Apocalyptic prophecies drive both sides to Syrian battle for end of time" By Mariam Karouny, Reuters, April 1, 2014:
"If you think all these mujahideen came from across the world to fight Assad, you're mistaken," said a Sunni Muslim jihadi who uses the name Abu Omar and fights in one of the many anti-Assad Islamist brigades in Aleppo.An excerpt from, "ISIS, other radical Islamists driven by Muslim eschatology" By Roger Drinnon, The Lutheran Church Missouri Synod, November 14, 2014:
"They are all here as promised by the Prophet. This is the war he promised - it is the Grand Battle," he told Reuters, using a word which can also be translated as slaughter.
"These hadith are what the Mujahideen are guided by to come to Syria, we are fighting for this. With every passing day we know that we are living the days that the Prophet talked about," said Mussab, a fighter from the Nusra Front, a Sunni hardline group linked to al Qaeda, speaking from Syria.
Murtada, a 27-year-old Lebanese Shi'ite who regularly goes to Syria to battle against the rebels, says he is not fighting for Assad, but for the Mahdi, also known as the Imam.
"Even if I am martyred now, when he appears I will be reborn to fight among his army, I will be his soldier," he told Reuters in Lebanon.
Since Muslims believe the establishment of a worldwide Islamic caliphate under the Mahdi’s rule is required to bring about a judgment day, Islamist extremist groups believe violent “jihad” (which linguistically means “struggle” but historically means “holy war against non-Muslims”) will hasten the establishment of the caliphate and thus the divine resolution of human existence. Furnish said some Muslims, especially certain Sunni groups, adamantly believe they can “hotwire the apocalypse.” This apocalyptic goal poses a dire threat to Christians and Western societies in general who are demonized as “infidels” not just by “extremist” Muslim groups but also in mainstream Islamic teaching, following the Quran and hadiths. The threat of groups like ISIS, also known as the Islamic State of Iraq and the Levant, or ISIL, continues to be evaluated at the highest levels of the U.S military.An excerpt from, "Apocalypse, Iconoclasm, and ISIS" By Naresh Kumar Nagothu, International Policy Digest, December 2, 2015:
“Some of them seek to establish a sense of political Islam and theocracy under [Islamic] Shariah Law, and some of them are apocalyptic … meaning they have such a worldview … that makes them, I think, especially dangerous,” said Army Gen. Martin E. Dempsey, chairman of the Joint Chiefs of Staff, during the Aspen Security Forum in July. “[ISIS] seeks a sense of religious legitimacy; its leaders believe they are the heirs to the Islamic caliphate … They can only sustain that religious legitimacy if they continue to succeed, so this is not a group that can go halfway. It has to keep moving toward its ultimate end-of-days, apocalyptic narrative or it will lose support, because it loses religious legitimacy.”
Furnish said other key elements of the Islamist strategy to establish the global caliphate include well-financed Muslim missionary propaganda, or “da`wah,” and forceful conversions to Islam. ISIS even has its own magazine called Dabiq. Funding for da`wah comes from a variety of sources including Saudi Arabs, non-state donors and ISIS’ illicit profits from criminal activities like human trafficking (a recent issue of Dabiq stated non-Muslims may be enslaved under Islamic law), smuggling and trafficking in looted archaeological artifacts. He also explained how hadiths allow for and even encourage Muslims to deceive non-Muslims with propaganda as part of the strategy for establishing the caliphate — a tactic known as “taqiyyah,” or allowable lying.
While the previous affiliates also sought refuge in history and tried to deploy skewed historical narratives they showed a considerable amount of disdain for apocalyptic or eschatological projects. For the Al Qaeda leaders and coterie, apocalypse or notions about eschatology were not particularly fetching. ISIS deviates from others here in the alacrity with which it has embraced such projects. The upsurge of interest and belief in apocalyptic tone has got to do with the instability and civil wars in the region. Massive changes at various levels coupled with unrest and disaffected nature of war in places mentioned as part of apocalyptic prophecies contrived to produce a material cum ideational cash cow in the form of a penchant for apocalypticism that ISIS has meticulously milked in its favor. Furthermore, having been left alone by the governments in Syria and Iraq in the two years after the departure of U.S forces certainly helped it in cementing its fledgling gains.