A definite trend toward secularization has occurred in the West, since the 1960s, among both Europeans and Americans as you state; however, in other parts of the world the reverse has occurred.
In the areas of the former Soviet Union, China, India, and Africa: exactly the opposite has been occurring. The percentage of Christians in these areas has grown tremendously and Christian church attendance has risen.
But let's return to look at the West a little closer. Though the West has become increasingly politically secularized (political secularization is not to be confused with state atheism) and the youth are much more inclined to not attend church services: religion continues to play a vital role in these countries.
I've read both of the recent PEW studies and they reflect what I observe in our society in my opinion.
1. Here's the first Pew study titled, “'Nones' on the Rise: One-in-Five Adults Have No Religious Affiliation":
‘No Religion’ on the Rise: 19.6% Have No Religious Affiliation - Pew Forum on Religion & Public Life
Look closer at the data and you'll see that many of the "Nones" who claim to have no religious affiliation believe in God with a good share of them attending services either regularly or only periodically as stated:
"Just 5% [of the unaffiliaged] say they attend worship services on a weekly basis. But one-third of the unaffiliated say religion is at least somewhat important in their lives. Two-thirds [of them] believe in God (though less than half say they are absolutely certain of God’s existence)."
Here's the second Pew study titled, "Not All Nonbelievers Call Themselves Atheists":
Pew Forum: Not All Nonbelievers Call Themselves Atheists
Look closer at you'll find that of the 5% of Americans that claim NOT to believe in a God, gods, or universal spirit: 14% of THOSE (e.g. atheists) simultaneously claim to be Christians! Crazy no?
To gain a better understanding of what's going on, you'll want to visit other scholarly religious primary data sources such as:
1. The World Religious Database [WRD]
http://www.worldreligiondatabase.org
2. The Association of Religious Data Archives
The Association of Religion Data Archives - U.S. and World Religion Statistics and Data - ARDA
They reveal some important insights. Despite the trending PEW brought out, the actual percentages of even post-Christian countries who claim the Christian belief system as their own are still very high. Consider the following post-Christian secular European nation statistics:
A. Sweden - 64.5% of Swedes are Christian:
Sweden, Religion and Social Profile | National Profiles | International Data | TheARDA
B. Denmark - 84.98% of Danes are Christian:
Denmark, Religion and Social Profile | National Profiles | International Data | TheARDA
C. Norway - 91.32% of Norwegians are Christian:
Norway, Religion and Social Profile | National Profiles | International Data | TheARDA
D. Belgium - 81.48% of the population in Belgium are Christian:
Belgium, Religion and Social Profile | National Profiles | International Data | TheARDA
When you dig further down, in the West, what you'll find are that very vocal but small minorities of atheists in very powerful positions in government, education, the media, etc... are working hard to change Western cultures to their way of thinking. But when emperical studies are conducted in Western societies, we find that most overwhelmingly still do care about God and Jesus Christ despite a definite measurable trend toward secularization and against Christian religious establishment.
Is the description growing numbers of people are giving themselves. Seems religions of all sorts are losing vast numbers of people. In fact since 9/11 with the responses of some major religions offer the attacks as retribution for just about any social problems; like gays or divorce or corruption.
Being "unaffiliated" with any congregation is very common now, are these people "Christians" must they profess the historical creeds, and attend church to get the label? Since nearly 40% of people are unaffiliated does that make America Post Christian?