I think it's easy to pontificate one way or another on the topic, but Ed Stetzer who's pretty fair in this regard, drilled down to some of the takeaways from recent Pew polls:
What seems most interesting, is that unless Christianity is "weird" or involves some sort of difference with society, it tends to disappear. For all of evangelicalism's flaws and failures, it's been able to reach younger generations at some level, albeit reduced levels. Mainline denominations have been unable to do this. It's funny, but while "country club Christianity" is the common refrain for Conservative groups, it seems the mainline denominations almost doubled down on this. It becomes hard to devote time to something that you don't fully believe in and only performs good works like many other atheistic or secular orgs. Barely maintaining half of your membership is astounding for any club or organization.
That said, there should be no glee in any quarter, because the fields are ripe and the workers are so few.
First, from 2007 to 2014 the number of evangelicals in America rose from 59.8 million to 62.2 million.
Evangelicals now make up a clear majority (55%) of all U.S. Protestants. In 2007, 51% of U.S. Protestants identified with evangelical churches.
Within Christianity, the only group retaining more of their population than the evangelical church is the historically black church.
That's not to say that evangelicalism is doing well—I think it peaked a couple of decades ago in the United States—but one of the big shifts INSIDE Christianity is TOWARD Evangelicalism, oddly enough. Yet, in the culture as a whole, and as a percentage of the population, Evangelicalism is losing ground.
Only 45% of those raised in the Mainline Protestant tradition remain in Mainline churches. Those whose parents and grandparents were mainline Protestants aren’t carrying on the family tradition like those who align with other Protestant denominations. Since members of these churches are not gaining new members from the culture at-large, nor growing by birth rates, they continue to decline precipitously.
I see this very much in my home state. In the old days, not going to church at least nominally might be enough to preclude a marriage or something similar. Now, those who do not hold faith are much more prone to publicly acknowledge that or even proclaim it. I think this is where a lot of the New Atheism schools of thought came from, and it has contributed to the vitriol of pushing Christianity from the de facto public square position it once held. Yes, that is uncomfortable for traditional Christians, and I think this is where some of the chicken little stuff comes from even within Evangelicalism.In short, and as I put it, the "nominals" are becoming the "nones" AND convictional Christian practice is a minority, but generally stable, population. If that is the case, and that is what the data is showing, than the decline is primarily (not exclusively) that nominal Christians are becoming honest reporters.
What seems most interesting, is that unless Christianity is "weird" or involves some sort of difference with society, it tends to disappear. For all of evangelicalism's flaws and failures, it's been able to reach younger generations at some level, albeit reduced levels. Mainline denominations have been unable to do this. It's funny, but while "country club Christianity" is the common refrain for Conservative groups, it seems the mainline denominations almost doubled down on this. It becomes hard to devote time to something that you don't fully believe in and only performs good works like many other atheistic or secular orgs. Barely maintaining half of your membership is astounding for any club or organization.
That said, there should be no glee in any quarter, because the fields are ripe and the workers are so few.