Robert Ferrigno came to my attention via a 2004 Slate article where various authors were asked for their presidential voting choices. The folks voting for Dubya were vastly outnumbered: Orson Scott Card, Roger L. Simon, Thomas Mallon, and Ferrigno. Here's his explanation:
Uh, wow. At the time, I was reading the Usenet group rec.arts.mystery; the above caused at least one sensitive soul to drop Ferrigno from her reading list. But it put him right on mine.
Ferrigno had been writing rather straightforward hard-boiled crime fiction, but this is a thriller set in a nightmarish near future. It's premised on nuclear terrorist attacks in 2015 which leaves New York City and Washington D. C. in rubble; a dirty bomb has rendered Mecca radioactive for the next few dozen millennia. The attacks are convincingly pinned on Mossad agents. This causes massive conversions to Islam in the US, and an eventual civil war between the evangelical-Christian old south and just about everyone else. Israel is destroyed, and everywhere else the market for kosher food goes way, way down.
The main part of the book is set when things have settled, thirty years later. Seattle, the new capital, is a mixture of religious despotism, ecological wasteland, and tolerated libertinism. (Go out of the cities, though, and things have devolved into a nasty-brutish-short Hobbesian fantasy.) The protagonist, Rakkim, is an ex-Fedayeen, ex-cop, now making a living transporting refugees to the relative safety of Canada. His true love, Sarah, has gone into hiding while doing historical research into the terrorist attacks. Her uncle, who happens to be Director of State Security, appeals to Rakkim to track her down. But even more deadly and mysterious figures also want to get their hands on Sarah. Conspiracy, betrayal, and danger abounds.
I don't know that an Islamic takeover of much of the US is very credible, but, on the other hand, I don't know that it isn't either. That aside, Ferrigno's imagined world is meticulously researched, much based on practices in actual "Islamic republics".
The book is the first in a trilogy, so I'm signed up for the others as well.