Second, the growth in Muslim populations across Europe since the mid-twentieth century runs parallel to secularization or, perhaps more aptly, de-Christianization. As Muslim populations grow and assert their religious identities in the public sphere, Christianity's public role and influence fade. In other words, the increasing presence and vitality of Islam is accompanied by the decreasing influence and presence of traditional Christianity. This trend is important because many Europeans have grown accustomed to thinking of religion as a private matter, not because they long to return to a period in which Christian leaders and institutions wielded greater power. Islam's presence and growth thus creates tension because it calls into question the secular values and assumptions that govern much of public and political life in Europe today. This tension feeds most contemporary conflicts between Muslim minorities and the majority populations of Europe.

Green, Todd H, The Fear of Islam_ An Intro…, loc. 342