RANIA, 51, is a Shiite Lebanese banking executive, married to a Sunni and living in Ras Beirut, one of the capital's few mixed neighborhoods.
When she married, at age 22, "I didn't even know what the difference between Sunnis and Shiites is."
Now she's inclined to support Hezbollah. While not a fan of the hard-line group, she believes that Hezbollah and Syria are targeted because of their stances against Israel. She said her husband is anti-Hezbollah and supports Syria's rebels.
Rania, who gave only her first name because she doesn't want to be stigmatized about her social, religious or marital status, said she doesn't talk politics with her husband to avoid arguments.
"I support one (political) side and he supports the other, but we've found a way to live with it," added Rania, who has a 22-year-old daughter.
She said education plays a big role. "I find that the people who make comments about it are the people who are just ignorant, and ignorance feeds hatred and stereotyping," she added.
KHALED CHALLAH is a 28-year-old Syrian Sunni businessman who has lived for years in Lebanon. He comes from a conservative, religious family but only occasionally goes to mosque. He said the only way he would be able to tell the difference between a Sunni mosque and a Shiite one would be if the cleric talked about Syria in the sermon.
"A Shiite imam would speak against the rebels, and call to resist them, and a Sunni sheik would talk against the government in Syria," he said.
He said he still doesn't understand the Shiites' emotional fervor over the battle of Karbala, in which Ali's son, Hussein, was killed by the armies of the Sunni Ummayad dynasty in the 7th century. Hussein's martyrdom is a defining trauma of their faith, deepening their feeling of oppression. Every year, Shiites around the world mark the battle with processions that turn into festivals of mourning, with men lashing or cutting themselves.
"It means much more to Shiites, this battle's memory, than to Sunnis," Challah said.
He said Sunnis "behave sometimes like they are the only Muslims."
Challah called this "very silly. Sunnis and Shiites come from the same root, they worship the same God."
The Shiite powerhouse of the Middle East is home to a government led by Shiite clerics with oil wealth and a powerful Revolutionary Guard. Tehran has extended its influence in the Arab world, mainly through its alliance with Syria, Hezbollah in Lebanon and Hamas in the Palestinian territories. Iran has presented that alliance not as sectarian but as the center of "resistance" against Israel.
Sunni Saudi Arabia and other Gulf allies have been trying to stem Iran's influence, in part by warning of the spread of Shiism. Saudi Arabia's hard-line Wahhabi interpretation of Sunni Islam views Shiism as heresy.
REZA TAJABADI, a Shiite cleric in Tehran, blames the Wahhabis — and the related ultra-conservative Salafi movement in Sunni Islam — for stoking sectarian hatred.
"If Wahabis withdrew from creating differences, then Shiites and Sunnis will be able to put aside their minor differences, which are not considerable."
ABOLFATAH DAVATI, another Shiite cleric, points to the historical difference between the two sects. Since Sunnis have been dominant through history, Sunni clerics became subordinate to the rulers. The Shiite clergy, he said, has been independent of power.
"Sunni clerics backed rulers and justified their policies, like the killing of Imam Hussein. Even now, they put their rulers' decision at the top of their agenda," he said.
"In contrast, Shiites have not depended on government, so Sunnis cannot tolerate this and issue religious edicts against them. This increases rifts."
In a country where the Muslim population is overwhelmingly Sunni, many Egyptians know little about Shiites. The Shiite population is tiny and largely hidden — so secretive that its numbers are not really known. But ultraconservative Salafis, many of whom view Shiites as infidels, have become more politically powerful and more vocal since the 2011 fall of autocrat Hosni Mubarak. They often preach against Shiism, warning it will spread to Egypt.