CAIRO -- In a drafty old cathedral, a priest in a pointed hat on Wednesday swung a tray of smoking incense and said a prayer. Shrouded women dropped to their knees in front of him, whispered in a mixture of Arabic and Greek, and wiped away tears.

Here in one of Egypt's oldest Coptic churches, mourners had come to pay their respects to a grocer killed 7,600 miles away.

Adel Karas, a Coptic Christian from Egypt who emigrated to Los Angeles two decades ago, was shot to death in his San Gabriel store four days after the Sept. 11 attacks on the United States.

Though U.S. authorities have not determined whether Karas was the victim of a hate crime, members of his extended family in Egypt say the cheerful grocer was slain because he was mistaken for a Muslim. He was an Arab, after all, and his mini-mart was next to a mosque.

"Adel was the light of our family," said his brother, Sami Karas, a Cairo physician. "And someone took him away, out of ignorance."

What happened to Karas has been taken as a warning by many Copts in Egypt: a war between civilizations has been declared, they say, and Arab Christians may get caught in the middle--in America or here at home.

Though U.S. officials have gone to great lengths not to cast American airstrikes on Afghanistan as attacks against Islam, many Muslims believe this is a religious conflict. Members of the Coptic minority in Egypt, persecuted in the past, worry that the fighting in Central Asia could reawaken anti-Christian feelings here and that they could become the proxy targets of those angry at the West.

"I hear them talking in the street," said Rafik George Labib, a mourner at Wednesday's service. "They don't know my religion, and they say in front of me what they want to do to Christians. It sounds bad."

Nearly two years ago, 20 Copts were killed during religious rioting in southern Egypt. In some rural communities, Christians have been told that if they don't pay protection money, they will find relatives face down in sugar cane fields.

Copts follow an ancient version of Christianity. However, they have adopted many Muslim traditions, including saying salaam aleikum, the typical Muslim greeting that means "peace be unto you."

Such complexities show that the Arab world, often seen as a hotbed for Islamic activism, is no Muslim monolith. Many countries in the Middle East, such as Lebanon, Syria and Iraq, have large Christian minorities, and as much as 14% of Egypt's population is Coptic. Two of Egyptian President Hosni Mubarak's Cabinet ministers are Copts, a point of pride for a group once blocked from higher office.

Christian-Muslim relations tend to be better in Egypt's big cities--where people socialize and do business across religious lines, though they rarely intermarry--than in rural areas.

"We usually get along mush mush kila [without problems]," said Cairo shopkeeper Abu Regala, a Muslim.

The question is: How durable is this relative peace?

This month, religious riots erupted in Nigeria, a nation divided between Christians and Muslims, after Muslim fundamentalists marched in the streets against the U.S. attacks on Afghanistan. More than 30 people were killed and hundreds of businesses were burned to the ground.

"If it happened there, why not here?" Adel Iskandar Abd Alla, a Christian jeweler in Cairo, asked with a fatalistic shrug.

In Egypt, reaction to the U.S. airstrikes often differs by religion. Most Muslims, from street sweepers to surgeons, are against the bombings. Many Copts, on the other hand, are for them.

Of 14 students recently interviewed at the University of Cairo, the only one who supported the action was an 18-year-old Coptic woman. "But it's not like I'm going to write my opinion on the wall," said Mariana Rizk, an economics student.

Youssef Sidhom, editor of Watani, a paper with a wide Coptic readership, said Christians aren't as touchy about the conflict. "We are not victims to this sentimentality, to this idea the strikes are intended to harm Muslims," he said.

Muslim militants, including Osama bin Laden, have tried to paint the Afghanistan airstrikes as a war between "true believers and infidels." In many quarters, they have succeeded.

So far there have been no reports of major Muslim-Christian clashes in Egypt. Last week, a Christian girl was slapped for wearing a cross at a student demonstration, and many Copts say they feel hostility gathering around them.

People spoke freely of their fears Wednesday behind the chipped brick walls of St. Mark's Cathedral in downtown Cairo. Most were members of Karas' extended family, and many wept as they looked at the grocer's photograph, placed near the altar beneath gold-leaf paintings of saints.

Karas, a 48-year-old father of three, was shot while standing at the counter of his grocery store. A witness saw three men leaving the scene. Investigators have not ruled out robbery as a motive, though Karas' family said no money was taken from the cash register.

"Adel was a man who lived well and with so much love," said a priest at the memorial service. "God bless our dead, God bless our loved ones and mercy, mercy on us all."