I read Ross Douthat’s book, Bad Religion: How We Became a Nation of Heretics.
Douthat essentially argues that at one point-from the mid 1950s to the mid 1960s-the Christian Church in America was a powerful, relatively united, voice in American society. This period in American life constituted a revival of sorts for orthodox religious faith, with the number of faithful growing, church life thriving, and generally a period in which America as a whole was a more devoutly Christian nation than ever.
Not coincidentally, during this period the Church also was a powerful force behind the civil rights movement, and provided more in the way of social services to the poor than at any time before or since.
Beginning in the mid-60s, a variety of cultural factors-materialism, the sexual revolution, birth of post-modernism, along with various errors, both theological and moral, by different mainline denominations, led to a decline in the mainline church. Today, once mighty denominations like the Methodists and Catholics are rapidly declining in membership and clergy. The fastest growing churches today, on the other hand, generally are either not Christian at all, really (Mormons), prosperity gospel-ish (Joel Osteen, et al). Some evangelical churches are growing fast (Saddleback comes to mind) but those churches are often affiliated with a certain conservative cultural and political bent, and thus are limited in their appeal to American society as a whole.
Douthat argues persuasively that this decline in the mainstream orthodoxy of American religion has had negative consequences not only for the souls of believers, but also the temporal state of American society as a whole. When religion becomes politicized, with the right and left wings going to different churches, religious leaders lose moral credibility to speak to the nation on issues of justice as they had in the past.
Of course, this book generalizes, as any 352 page book that attempts to cover 6 decades of a cultural movement as broad and diverse as American Christianity must. But Douthat recognizes the generalization and the counter-examples to his point, and still musters persuasive data to support his argument that American Christianity has a weaker influence on the culture now more than ever. Anyone who is concerned about Christianity in America should read this book.