The author's supposition might have some traction when applied to western Europe. However, as it comes to the United States, I think the figure of 38 years is ridiculously optimistic. Despite pedophile priests and philandering pastors, the sheeple who make up the congregations of churches in the US either dismiss or refuse to see the obvious flaws in the organizations they so willingly participate in.
The reason is simple: it's the easy way out. To do otherwise is to swim against the tide, risk censure and derision, never mind the simple fact of Having to Exert Oneself where one doesn't really HAVE to. The status quo is just fine to them and they are perfectly willing to continue floating downstream.
Our children or their children might see the day when religion in the US is reduced to a bizarre curiosity. I have no such expectation.
Postscript: As regards countries where islam is the dominant belief, those areas will be likely multiple CENTURIES before they can shrug off the yoke which imprisons them ... IF EVER.
I honestly hope so. But I think we need to step up our efforts.
I suppose it would be wonderful if a more realistic mindset could be applied to national policies and human interests. So, it would be great if disbelief took the lead over religion.
However, such a phenomenon -- if it ever happened -- is not a guarantee of a better world. The path is not ipso facto rosier and more abundant if religion takes a back seat to free-thought. People, despite their philosophical dispositions, will still make attempts at exerting control over the masses; politics will still gravitate toward nannying the population; stuff will not necessarily get better in many, many key areas of human existence.
So for me, the question ends up being, how does atheistic leadership ensure more altruistic human interaction?
The look at trends in Christianity began with studies by Christian groups whose minister-members were all noting how much older their populations were. Too many churches were closing, and they wondered if their ex-members were all going to the mega churches that had risen in popularity. These studies shocked Christian leaders, leading them to begin talking about the prophecied ending of the church age.
The most exciting from my point of view (but disturbing from theirs) was the fact that of those between 18-23, ONLY ONE HALF OF ONE PERCENT have a Biblical worldview. (The Bible is absolute truth). This number jumps considerably with increasing age, but it has died out in the northeast as retirees move to the sun belt, where numbers are seen growing. It was also interesting to note that those who attend a Christian college graduate with a seismic shift in their thinking, as seen by the fact that only 19% of those graduates still have a Bible as inerrant worldview.
Even when counting those who do not believe in absolute morality, the numbers of young people going to church is surprisingly low. Unfortunately, young people don't vote in very large numbers, so it will take a while to see their view of equality under the law emerge in our culture, but it is on its way.
2038? Plausible. That's only about 20 years from when the original poll was taken, which means that these people will be in their 40s and the number of them voting (if America is still in existence) will start increasing dramatically.
The question is whether or not America will still be in existence. Our current fiscal paradigm is unsustainable. When it collapses, will religion prey on its victims as the study your link referenced indicates that it does?
I'm extremely hopeful. I've seen a dramatic increase in people who share my worldview. In the 1980s, when my worldview started coming together, I didn't know a single soul who believed what I believed or was even interested in pursuing knowledge then becoming available (perhaps because of the lack of a mature Internet). Now I meet like-minded people in all sorts of forums.
I have watched the backlash against the Christian fundamentalists who are actively working to discriminate against women and the LGBT community. Note that in the last election, fundamentalist christian views worked against the candidate (unless the candidate was an incumbent.) That's a good thing.
I'm not certain about "Defeat" in 2038, but within the next decade, their will be a paradigm shift
in the western world. Freethought is rising.