The Alawis claim to trace their origin from the 11th imam, Hassan Al-Askari. Abu Nusayr was said to the the student of Imam Hassan al-Askari, though this isn't confirmed. However, Nusayr's ideology deviated into a very different and un-Islamic path by assigning divinity to Imam Ali, a theory that was completely rejected.
Late Hafez al-Assad of Syria declared the Alawites must follow the same doctrine as the Twelver Shiias (that is, the majority Isn-e-Asheri denomination of Shiias .. same as the Shiias of Iran). Bashar al-Assad has continued to maintain the framework of his father's governance. In fact, under the directions of the Assad government, the Alawite culture has also moved very close to Sunni Islam. Assad senior had set several examples for the people by adhering to various Sunni practices. The online encyclopedia writes "The Alawi religion evolved during the years under Hafez Al Assad's rule, so that Alawites became not Shiia, but effectively Sunni. Public manifestation or even mentioning of any Alawite religious activities was banned, as was any Alawite religious organizations or any formation of a unified religious council or a higher Alawite religious authority. Sunni-style mosques were built in every Alawite village."
In the mid 1970s, Musa Al-Sadr, founder of the Amal Movement in Lebanon, a very senior mainstream Shiia leader and follower of the twelve imams issued a fatwa that the Alawites belonged to the community of Twelver Shiia Muslims.
Some hardline medieval Sunni scholars such as Ibn Kathir declared Alawites as "pagans" because of the Nusayri ideology. Although later the Nusayri doctrine was completely trashed by the Alawites, such official declarations by the medieval imams have had far-reaching consequences. They are still serving as the foundation for sectarian differences, as an outcome of which, the bulk of the Sunni world is supporting the West in the present Syrian conflict.
Under the Assad government, religious minorities have been tolerated far more than they were prior to the 1970s which has led many closed minded observers to presume that Alawis are staunch secularists or even "heretics." That's of course nonsense and quite the opposite of what people claim. Tolerance of minorities is a factor much in line with Quranic values. The Syrian constitution of 1973 upholds that the religion of the republic's president is Islam instead of the state religion being Islam as asserted before - a statement that was often misinterpreted by hardliners. Issues like these have periodically been blown out of all proportion by firebrand traditionalists, issuing fatwas and declaring Assad's government as "deviants."
It's about time for Muslims to be open-minded and to monitor the truth, otherwise only our imperialist enemies will be the beneficiaries.