I don't keep up with statistics. They're too easily manipulated--intentionally or accidentally, in polling or presentation--to fit the user's needs; because I'm jaded toward them, I'm also useless in making generalized statements that depend on statistical data to have some shred of usefulness. That said, I can't comment on "the world." I can, however, share that a lot of my old peers at Bible college were without home churches; many students barely even put in the effort to float from church to church unless required for assignments.
That is saddening. I confess that it can be hard to find a church to call "home" (though I've been fairly consistently going to one local church for a couple months now, I have a hard time finding a church since moving to Florida to call "home"). Still, it does seem to correlate with the idea of "this generation's lackluster church attendance."
My oversimplified estimation is that there is also a connection to many churches trying to be culturally relevant through human means (cutting edge music and technology, hip preachers, coffee shops, etc.--not that these are bad things in themselves, of course--or through "sanitizing Scripture" to make it less threatening to the unchurched). In short, attempts by human means to become relevant only makes a church more irrelevant to those already saturated in culture. It seems to me that there is better music, better teaching, and better coffee to be had outside the church, and what reason do I have to go to church if I'm just getting the same watered-down call to being less of a jerk anyway? It seems to me that cultural relevance is found not by trying to catch up to culture (because really, who among us actually wants to wake up and go somewhere only to get Jesus-ified trends and consumerism thrown at us?) but by living out the counter-cultural Gospel of love, peace, grace, and holiness all bacon-wrapped in humility. Rather than trying to play catch up with the things the world already offers, we should be offering what the world cannot: True relationship with God through the sacrifice of Christ displayed in our lives as we learn to know and love Him more.
Back to the experience of self and Bible college friends, it is interesting to note that those of my friends who've made the jump from evangelical Protestant churches to mainline Protestant, Catholic, and Orthodox churches are typically the ones most genuinely enthused about church involvement and living like the church whether they're at church or not. It may very well be coincidence, but it's interesting nonetheless.
I apologize for this possibly coming off as a dig at evangelicalism or evangelical churches (especially since my guess is that most here are evangelicals, myself vaguely included, many even in church leadership); I hope it goes without saying, but I have no such ill intent. I have highest respect for the countless leaders in evangelical churches and the multitudes of evangelical laypeople. It has just been, in my limited experience and in the talking with friends, that evangelical churches are the most prone to playing cultural catch-up, and it's that game of cultural catch-up, not evangelicalism itself, that makes attendance and involvement that much less appealing.
That said, we should always be aware of cultural trends and desires, and I totally agree with and commend the church leaders (which especially includes those same evangelicals) who are open to adapting to an ever-changing culture. We should never let a reluctance to change (as in simply being unwilling to consider change, regardless of what the specific issue is) be a hindrance to spreading the Gospel. If a congregation would be better suited by a rock band than the organ and piano used for the last 50 years, then change can certainly be a good thing. It only becomes a problem if we change for the sake of change, or if we bring in that rock band hoping that it will
attract newcomers even though it doesn't suit our congregation; if we're changing in attempt to play cultural catch-up or otherwise generate mass appeal, then we probably need to think a little harder about our priorities/motives and whether we're trying to be relevant by human means or divine means before moving forward with it.
Most of my Christian friends who aren't involved in a local church tend to be uninvolved because they don't feel it is worth the time or relevant, even when they have gone to churches doing their best to be up-to-date. It's not that they have an aversion to church; it's that they don't have a motive for attendance other than going for the sake of going.
Thaaat's a wall of text with a lot of wandering. I shouldn't do this late at night. heh I hope this is more relevant to where you were hoping the conversation would go, though.
Edit: In my estimation, we need more of this if we're wanting to be culturally relevant, real hope for a world that needs it:
Psalm 46
[7] The LORD Almighty is with us;
the God of Jacob is our fortress.
[8] Come and see what the LORD has done,
the desolations he has brought on the earth.
[9] He makes wars cease
to the ends of the earth.
He breaks the bow and shatters the spear;
he burns the shields with fire.
[10] He says, “Be still, and know that I am God;
I will be exalted among the nations,
I will be exalted in the earth.”