Today, Rep. Peter King (R-NY) will continue to hold Congressional hearings on the radicalization of Islam in America. I have not heard that he will call a professor of ninth century Spanish history, but he should. The story of the Moorish occupation of Spain may will shed light on many facets of the current situation, though the limits of the parallel are obvious.
I don't pretend to be expertise in either the ninth century or Spain, but as Paul Burns tells it in Butler's Lives of the Saints, the Moors established a fairly moderate Muslim regime following the conquest of Spain. Christianity was tolerated, though Christians paid a surtax on their faith and were subject to restrictions. Two brothers were executed in 822 for insulting Islam, but no further religiously-driven executions followed until 850. During that time, some Christians paid their taxes to keep their faiths, but others converted or intermarried, resulting in their children being Muslim.
A priest named Eulogius began to foment more active resistance to Muslim domination of Spain. Two daughters of a mixed marriage were executed for apostasy; having some Muslim ancestry, they were considered by the court to be automatically Muslim. If they proclaimed themselves Christian, that was prima facie evidence of apostasy. A priest named Prefectus and a monk named Isaac were executed for defaming the Prophet Mohammad.
A new Moorish king, eager to lay down the smack, came to power in Spain. Lots of executions followed. Many Christians rushed to embrace martyrdom -- a longstanding phenomenon in minority faiths. Eulogius was persuaded to try to put the Christian resistance back in its bottle, but then he was busted for harboring an apostate. Both he and the apostate, Lucretia, were executed.
The reversal of fortunes for Moors in Spain was not immediate, but it was brutal. Spain developed into one of the most infamously religiously intolerant regimes in Europe.
The implications for a religiously tolerant, pluralistic country in the twenty-first century? I'm not sure. One could look at the Moorish regime's sensitivity about insults to religion. One could look at the government's inability to suppress the desires of the people, whether the apostasy law or the unequal treatment of religions. One could look at the inherent characteristics of Christianity and Islam, questioning whether what was true in ninth century Spain is true in another time and place. I don't know nearly enough to draw conclusions, but I think Representative King might do well to consult someone about it for an hour or so.