It is not that the two are mutually exclusive; but they are not necessarily linked. As Egyptians increasingly emphasize Islam as the cornerstone of identity, there has been a growing emphasis on public displays of piety.
For women, that has rapidly translated into the nearly universal adoption of the hejab, a scarf fitted over hair and ears and wrapped around the neck. For men, it is more and more popular to have a zebibah.
The zebibah, Arabic for raisin, is a dark circle of callused skin, or in some cases a protruding bump, between the hairline and the eyebrows. It emerges on the spot where worshipers press their foreheads into the ground during daily prayers.
It may look like a painful wound but is worn proudly in Egypt, along the lines of American professionals in the 1980s who felt good about the dark circles under their eyes that testified to long work hours and little sleep.
Two decades ago, Egypt was a Muslim country with a relatively secular style. Arabism and nationalism traded places as the foundation of identity. But today, Egypt, like much of the Arab Middle East, is experiencing the rise of Islam as the ideology of the day.
With that, religious symbols have become the fashion.
"The zebibah is a way to show how important religion is for us," said Muhammad al-Bikali, a hair stylist in Cairo, in an interview last month. Bikali had a well-trimmed mustache and an ever so subtle brown spot just beneath his hairline. "It shows how religious we are. It is a mark from God."
Observant Muslims pray five times a day. Each prayer involves kneeling and touching one's forehead and nose to the ground. The five prayers require placing one's head on the ground for a total of 34 times, though many people add additional prayers and with that, additional chances to press their heads to the ground. Some people say that the bump is the inevitable result of so many prayers - and that is often the point: The person with the mark is broadcasting his observance, his adherence to one of the five pillars of Islam.
But the zebibah is primarily a phenomenon of Egypt. Muslim men pray throughout the Arab world. Indeed, Egyptian women pray, but few of them end up with a prayer bump. So why do so many Egyptian men press so hard when they pray?
"If we just take it for what it is, then it means that people are praying a lot," said Gamal al-Ghitani, editor in chief of the newspaper Akhbar Al Yourm. "But there is a kind of statement in it. Sometimes as a personal statement to announce that he is a conservative Muslim and sometimes as a way of outbidding others by showing them that he is more religious or to say that they should be like him."
There are many reasons for the Islamic revival that has swept Egypt and the Middle East, from the rise of satellite television that offers 24 hours a day of religious programming, to economies that offer little hope of improving one's life, to the resentment of Western meddling in the Middle East. But there is also peer pressure, a powerful force in a group-think society, where conformity and tradition are aspired to and rewarded.
"I will learn more about someone when I get to know him, but the appearance is the first impression," said Khaled Ashry, 37, a security guard at a private school.
Hanaa el-Guidy, 21, an art student in Cairo who covers her head and wears a long and loose-fitting dress to hide her figure, said: "The outward appearance is important. It says, 'I am a good person.' This is a good thing. On Judgment Day, this sign, the zebibah on their forehead, will shine. It will say 'God is great.' "
In much of the Arab world, symbols of extreme observance are fairly standard and tend to stem from the conservative religious cultures of Gulf nations, like Saudi Arabia. There is the long beard. In extreme cases men wear a loose-fitting robe that stops at their ankles, in keeping with a tradition that the Prophet Muhammad wore his own gown at ankle length.
Those symbols have seeped their way into Egypt, and are growing in popularity. More and more women, for example, are covering their faces with a niquab, a black mask of cloth that has come to Egypt from the Gulf.
The zebibah, however, is 100 percent Egyptian, and it does not carry any of the negative connotations of imported symbols. Men with long beards can still find it hard to get a job. The zebibah, on the other hand, can open doors.
"The zebibah can help," said Ahmed Mohsen, 35, a messenger for a law firm whose own mark was pinkish, bumpy and peeling. "It can lead to a kind of initial acceptance between people."
There are no statistics on the zebibah's prevalence. But today, perhaps more than any time in recent history, Egyptians are eager to demonstrate to each other just how religious they are.
There are many rumors about men who use irritants, like sandpaper, to darken the callous. They may be apocryphal, but the rumors themselves reveal how fashionable the mark has become.
Of course, not everyone has a zebibah. There are still plenty of Egyptians who feel their faith is a personal matter.
But the pressure is growing, as religion becomes the focus of individual identity, and the most easily accessible source of pride and dignity for all social and economic classes.
"You pray, but it doesn't come out," said Muhammad Hojri, 23, as he gently teased his brother, Mahmoud, 21, one day recently while they worked in a family kebab restaurant. Muhammad has a mark. Mahmoud does not, and he didn't appreciate his brother's ribbing. "I pray for God, not for this thing on my forehead," Mahmoud shot back.