The Boston Marathon bombers, Tamerlan and Dzhokhar Tsarnaev, appeared to be thoroughly assimilated immigrants in 2013.

Many Americans looked at the Tsarnaev brothers at that time and asked how they went undetected as jihadists. They wondered how two brothers could lead seemingly normal lives while an infectious jihadist ideology ate at them from the inside. Because the brothers were clean-cut guys who went to the gym and partied with their American friends, even the media asked how they could have committed these “senseless deeds.”

Few seemed to grasp that a conversion to religious fanaticism can happen silently without showy displays, or without a traceable support community. Those who asked such senseless questions didn’t understand that to a jihadist, violence and murder are not senseless.

In our secular age — where religion is often seen as an irrelevant inheritance from the past — the study of religion is pushed aside as a useless endeavor. Those who don’t care much for religion themselves may tend to dump all sects and creeds together in one massive Dinty More’s Beef Stew: “Being a Presbyterian is no different than being Amish or a Muslim, etc.” This is why, after every Islamic terrorist attack, so many clamor: “It’s not Islam! It has nothing to do with Islam!”

After the Boston tragedy, I happened upon a report on the building of a $50M Islamic Cultural Center ten miles north of Dublin, Ireland. Ireland, a country of some 4.6 million people, used to be a robustly Catholic country. Today Muslims constitute about 1.07% of the population, but the Pew Forum on Religion and Public Life forecasts 125,000 Muslims in Ireland by 2030.

It is a well-known fact that immigrant Muslim populations do not often assimilate into the cultural life of their new nation: instead, they form parallel communities. While some may argue that Italian and Irish immigrants did the same when they immigrated to the United States, the parallel communities those groups formed did not seek to change the customs, laws, and social mores of the host country. This is what had critics of the Dublin mosque up in arms. They feared the newly created suburb around the mosque would become the genesis of a Muslim community that would eventually challenge Ireland’s governance.

The critics of the Dublin mosque were not guilty of paranoia; one has only to read the tsunami of books about the Islamization of Europe. Consider Pamela Geller’s Fatwa, Bruce Bawer’s While Europe Slept, or Robert Spencer’s Confessions of an Islamophobe. Observations concerning the Islamization of Europe through immigration and refugee-coddling go back to 2001, when the great Italian journalist Oriana Fallaci published The Rage and the Pride.

Fallaci wrote of a Muslim encampment in her home city of Florence:

An enormous tent erected by Somali Muslims to blame the Italian government that for once hesitated to renew their passports and to accept the hordes of their relatives. Mothers, fathers, brothers, sisters, uncles, aunts, cousins, pregnant wives, and possibly the relatives of relatives. A tent erected next to the Archbishop Palace on the sidewalk on which they used to leave their shoes and the bottles of water with which they washed their feet before the prayer. Therefore placed in front of the Santa Maria del Fiore Cathedral and a few steps from the Baptistery. A tent furnished like a small apartment: tables, chairs, chaise-lounges …

In Philadelphia, there are Muslims of Middle Eastern extraction. However, a majority of converts to Islam in that city are black Americans. Many of the men converted in prison, and their wives or girlfriends often followed suit not for theological reasons, but for love. Race identification and group solidarity are often at the root of this black American fascination with Islam (the devil is represented as a white man with blue eyes, etc.). As a result, black Muslims in the city appear to be as far from having jihadist tendencies as any random Catholic nun. In Philadelphia, one even gets the sense that many of the women dressed in full hijab boarding the subways and shopping at Macy’s really don’t have a clue about their religion. The heavy female Muslim dress spectacle in Philadelphia comes across as a never-ending masquerade.

Doris, a Pakistani friend who spent years looking for a husband, used to call me occasionally and tell me about the men she was dating. When she finished medical school a few years ago and became a pediatrician, she finally got engaged and invited me to the wedding. I imagined a Unitarian or a non-denominational service, since Doris had always described herself as a Unitarian. When I arrived at the wedding venue and noticed that it was called the Palace of Asia restaurant, I knew I was in for a surprise.

Doris wore a full Indian sari, covered with thick gold ornamental jewelry, her face framed by a long free-flowing veil. The man standing beside her in a bejeweled Nehru jacket did not look like a Unitarian by any means. In addition, the “champagne” they were serving at the pre-dinner reception was not wine at all, but sparkling apple cider as well as a variety of other carbonated juices. Many of the women in the restaurant wore exotic head scarves.

My confusion ended when a man in a suit introduced himself as the imam, and explained the rubrics of a Muslim wedding. Doris’ mother told me that her daughter had converted to Islam just two weeks before.

I wondered if underneath all of Doris’ thick ornamental jewelry she still wore the tiny gold cross that I had seen around her neck for years. I also wondered if my heretofore carefree friend would spend the rest of her life shrouded in long veils, or other face coverings.

Not long after Doris’s marriage, I attended a lecture by Tom Trento, an evangelical Christian and a member of the Florida Security Council; he came to Philadelphia to showcase the documentary The Third Jihad. Among those interviewed in the film was Ayaan Hirsi Ali, the former member of the Dutch Parliament who made the short film Submission with Theo Van Gogh. Van Gogh, of course, was later killed by an Islamic radical for his portrayal (in Submission) of the treatment of women in Islamic societies.

At the end of the film, Trento spoke about “the silent jihad in Philadelphia.” That got me thinking about those Muslim women running around in Macy’s in full head and face coverings. Trento’s phrasing gave me a chill because it suggested that most Americans are asleep when it comes to the silent jihad happening all around them.

Could Philadelphia be a sleeping target?

After the lecture, I realized it had been over a year since I had last heard from Doris. Was her husband forbidding her to call? Had the worst aspects of radical Islam trapped her in its grip?

I gave Doris a ring.

On the phone, she was her old charming self, talking about her beautiful daughter and her job at a large hospital. Then, in a quick turnabout and as if she was reading my mind, she stated that she had become a Muslim for the sake of her marriage. “I don’t really believe any of it,” she emphasized, “and I certainly don’t follow any of the rules.”

Then she shocked me one more time by adding, with her trademark cascading laugh: “These people are really nuts!”