RealClearWorld has an article by David Voas looking at trends in religious belief in the U.K., with the attention-getting title "Is Christianity Dying in Britain?" The short answer is "yes, slowly."
Young people are not going to church nor do many consider themselves Christians. As older church members die off, Britain becomes progressively less Anglican, less Christian.
Among those born since 1975 - nearly everybody under 40 - twenty-five percent do not believe in God and another 22+ percent don't know if there is a God and don't much care. Taken together, almost half of the under-forty cohort in Britain is either atheist or agnostic.
Much the same thing is occurring across Western Europe. Preliminary evidence from other sources suggests to COTTonLINE the same trends exist in the United States, although not as far along as in Europe.