Europe's religious crisis, referenced in Jenkins's title, is actually a demographic crisis. For a society to maintain its existing population size, it requires a fertility rate of 2.1 children per woman, and the fertility rates in most European countries fall well below that number. Along with the birth dearth, for decades Europe has been home to large-scale immigration, particularly from Muslim societies, and an immigrant population whose birthrate outstrips that of native Europeans. Warnings that the continent will become home to a Muslim majority before the next century are underscored in Europe's Muslim communities by a strong extremist voice, a reluctance to assimilate, widespread support for Shari‘a (Islamic law), and homegrown terrorism.
Concluding that "the most pessimistic Eurabian visions" are "wildly unlikely," Jenkins argues that Europe's secularizing forces are so strong that the continent will impose upon Islam "an ever more adaptable form of faith that can cope with social change without compromising basic beliefs." Jenkins foresees a wave of secularization spilling into Africa and the Near East and thinks the encounter with Islam may revive European Christianity. But these assertions lack the balance and foresight of Jenkins's previous demographic study about Christianity's future, The Next Christendom: The Coming of Global Christianity.
The quality of Jenkins's research, however, has not wavered. He offers the best examination yet by any author of the subject but downplays the problems he himself has uncovered. For example, Jenkins details the alarming disavowal by Western nations of bedrock rights when they offend Islamic sensibilities. After violent protests followed a Danish newspaper's publication of cartoons satirizing Muhammad, government officials vowed to prevent a recurrence. One European Union commissioner argued for a voluntary code of media conduct to signal that "we are aware of the consequences of exercising the right of free expression … and we are ready to self-regulate that right." Such weakness by Europe's establishment calls into question Jenkins's faith in its ability to sustain the continent's commitment to secularization.
Moreover, his argument about European Islam's inevitable secularization lacks the thoroughness that has earned him a deservedly strong reputation. He writes that "no evidence suggests that Islam is any more immune to secularizing forces" than Christianity, but this is untrue. Bernard Lewis has noted that Christians interpret Matthew 22:21 ("Give to Caesar what is Caesar's") as authorizing secular politics. In contrast, the idea of religious rule embedded in Muhammad's example frequently makes the notion "that any group of persons, any kind of activities … is in any sense outside the scope of religious law" appear "alien to Muslim thought." While this distinction may not prove insurmountable, Jenkins does not even consider it
Jenkins's argument is shaped by his concern that European elites misapprehend religion as a whole. While the concern is valid, there is a clear disconnect between Jenkins's research and his conclusions.
 Oxford University Press, 2002.
 Bernard Lewis, What Went Wrong? The Clash between Islam and Modernity in the Middle East (New York: Perennial/HarperCollins, 2002), pp. 96-100.