Despite that, many Alawites initially joined the uprising against Bashar al-Assad, calling for greater freedom and government transparency.
As the conflict progressed, however, Sunni rebels targeted Alawite communities, pushing them back into Assad's arms.
To give you some sense of how some Syrian Sunnis feel about Alawites, here's what Adnan Anour, a cleric who fled to Saudi Arabia, has said: "As for those Alawites who violate what is sacred, when the Muslims rule and are the majority of 85%, we will chop you up and feed you to the dogs."
In May it appeared the rebels had the momentum and Assad's fall was just days away. Then Hezbollah, a Lebanese militant group, announced that it was joining the fray, and backing Assad.
Within weeks, this fierce group, led by Hassan Nasrallah, had managed to wrestle key cities from rebel control, turning the war's tide.
There aren't many Shiites in Syria, but the Assads courted them from neighboring Iran, Iraq and Lebanon, allowing them to build major shrines to the faith's founders in Syrian cities.
The strategy seems to have worked.
When Sunni rebels attacked those shrines, Shiites rushed in to defend them. Not that Sunnis and Shiites need many excuses to fight. They've been battling since the earliest days of Islam and continue to clash in Iraq and other countries.
Nasrallah harkened back to those early clashes when Hezbollah joined the battling, calling the Syrian Sunni rebels "murderers of Hussein."
Hussein ibn Ali was the Prophet Muhammad's grandson who refused to pledge allegiance to the ruling Muslim caliph in the 7th century. Shiites believe that he and his family were the rightful rulers of the Muslim community.
Sunni Muslims are by far the biggest Muslim sect, in the world and in Syria. It's estimated that Sunnis make up 75% of Syria's population of 22 million. But they've long been sidelined by the Assads.
It's little surprise, then, that most of the Free Syrian Army, the largest rebel group, is Sunni.
Within the FSA, the Sunnis break down into remnants of the Muslim Brotherhood, who were brutally suppressed by the Assads; Salafists, who believe in a purified Islam based on its earliest days; and more secular-minded Sunnis.
In recent months they've been joined -- sometimes to their consternation -- by fighters from al Qaeda-linked groups. Always eager to fight Shiites and sow discord, these jihadists are every bit as fierce and battle-tested as Hezbollah, their sworn enemy.
It's unclear, however, how al Qaeda itself is involved in Syria.
The Iraqi-branch commander reportedly overstepped his authority in June by announcing a merger with Syria's al-Nusra Front, earning a smackdown from Ayman al-Zawahiri, al-Qaeda's global leader.
At the same time, some Syrian fighters say they pretend to be al-Qaeda just to annoy the Assad regime.
Still, prominent Sunni Muslim cleric Sheikh Yusuf Qaradawi has called on all Sunnis to join the fight against the Shiites and Hezbollah, calling them Hizb al-Shaytan, the “Party of the Devil”
Saudi Arabia and Qatar are backing that call with their wallets, according to international reports, hoping to prevent Shiites from gaining a stronghold in the region.
Christians, who form about 10 percent of the Syrian population, are essentially middle men in this civil war, caught between Assad's army and the Sunni rebels.
Under Assad, Christians had more rights than in many Middle Eastern countries, with the freedom to worship and run schools and churches. Their rights were limited however. The Syrian constitution says the president must be Muslim, for example.
According to UN reports, rebel fighters have targeted Christian communities, shooting up factories and detonating car bombs in Christian neighborhoods.