From the Gallup Poll site:
More than 9 in 10 Americans still say "yes" when asked the basic question "Do you believe in God?"; this is down only slightly from the 1940s, when Gallup first asked this question. ... Despite the many changes that have rippled through American society over the last 6 ½ decades, belief in God as measured in this direct way has remained high and relatively stable. Gallup initially used this question wording in November 1944, when 96% said "yes." That percentage dropped to 94% in 1947, but increased to 98% in several Gallup surveys conducted in the 1950s and 1960s. Gallup stopped using this question format in the 1960s, before including it again in Gallup's May 5-8 survey this year.
Belief in God drops below 90% among younger Americans, liberals, those living in the East, those with postgraduate educations, and political independents.
However, past Gallup surveys have shown that not all Americans are absolutely certain in their beliefs about God. Given the ability to express doubts about their beliefs, the percentage who stick to a certain belief in God drops into the 70% to 80% range. Additionally, when Americans are given the option of saying they believe in a universal spirit or higher power instead of in "God," about 12% choose the former. Still, the May 2011 poll reveals that when given only the choice between believing and not believing in God, more than 9 in 10 Americans say they do believe.
Also noted is that at "some points in the 1950s, almost all Americans identified themselves with a particular religion. In recent years, more than 1 in 10 Americans tell survey interviewers they have no formal religious identity."
(The poll did not ask how many people believe that the New York Times is God or is a mouthpiece for God.)
It is rather easy to say, "I believe in God", just as it is easy to say, "Love is the answer", "Let's build a better world together", or "I prefer two shots of espresso in my latte", as these statements are open to a wide range of interpretation (except for the latter, as "two shots" and "latte" are fairly recognizable entities, even to the most non-dogmatic java junkie). Vague talk about "God" and "love" only goes so far, and that's not very far in the year 2011, when a fair number of people believe that they are God (or part of God) and that homosexual acts express love just as truly (if not more so) than the marital embrace.
That said, the numbers still surprise me in a good—if also cautious, qualified, and muted—way. After all, recent polls in Britain indicate that some 30% or more of Brits (perhaps even a majority) don't believe in God. This trend (in England) and some of the social, cultural, and religious reasons for it are examined in depth in Hugh McLeod's book, The Religious Crisis of the 1960s (Oxford, 2007), which I've been reading recently in bits and pieces. McLeod (who acknowledges his liberals views, but whose analysis and insights are usually quite excellent) traces the roots of the upheaval of the 1960s back to the Sixties: the 1860s. He notes that "since the 1860s and 1870s agnosticism had fashionable in sections of the intelligentia. The pioneers of this movement had attacked Christian doctrine while largely accepting Christian morality." By the 1920s, however, influential thinkers such as the atheist Bertrand Russell were attacking "convential morality" openly and with growing success. McLeod details how liberal Anglicanism was at the forefront of the eventual collapse of long-held beliefs about morality, God, and the importance of Christian faith. One aspect of this trend was that morality was increasingly seen as necessarily distinct—even radically separate—from the sphere of law:
The other important development at this time was the increasing respect by Anglican leaders for 'experts', such as doctors, psychiatrists, and sociologists, leading to the view that Christian ethics, rather than being autonomous, had to take account of the latest evidence coming from these other disciplines.
This set the stage for the acceptance by the Anglican hierarchy of contraception, which was increasingly believed to have a vital role in making marriages more happy and successful. McLeod places much emphasis, notably, on the role of changes in law (what he terms the "legislative revolution"), concuding that "the legal reforms of the 1960s and 1970s mark an important state in the decline in Christendom, and the move towards a pluraistic society, in which a range of contrasting moral standpoints have an accepted standing." But he notes that while the religious trends of the U.S. and western Europe were very similar from 1945 to 1972, those paths "began to diverge" around 1972. While church-going continued to plummet in Europe, Canada, Australia, and New Zealand, it stabilized in the U.S. There is much more to McLeod's analysis, which is quite illuminating, but he writes that the
differences between Europe and the United States are not so much therefore between the 'secularity' of one and the 'religiosity' of the other, as between different ways of being 'secular' and of being 'religious'. ... The biggest difference between the United States and most parts of western Europe, I have suggested, lies in the degree to which religion continues to be embedded in American popular culture, in spite of the secularization of many elite groups. A second difference is that professions of piety are required of American politicians in a way that seldom happens in Europe, and this probably has done more than anything else to shape perceptions of Americans as an unusually, and perhaps excessively, religious people.
What to make of all of this? I'm not entirely sure, but it seems fairly obvious that the polarization in the U.S. between "liberals" and "conservatives" has as much to do with religious beliefs as it does with policy, perhaps even much more so. In other words, it seems to me that many Americans inately recognize, however imperfectly, that politics are rooted in ethics, which is grounded in morality, which in turn comes from God (however vaguely "God" is defined), whereas those with a more secular or liberal bent see politics as more foundational, informing notions about religious practice and belief. Also, I think the growing trend of believing in God while refusing to be a member of a particular church or denomination will grow, as evidenced in part by the increased talk among many Protestants of a "post-denominational church" (as opposed, I suppose, the pre-denominational Church founded by Christ). And I think that the talk about "God" divorced from substantive doctrine and some sort of meaningful tradition leads fairly inevitably to either practical agnosticism/atheism or wholesale rejection of Christianity.
For an interesting perspective from some eighty years ago or so, see this piece from Monsignor Ronald Knox: