I need someone good at math!!!

[periwinklefish]

The percentage of atheists (now) is anywhere between 15-20%.  (15% admitted, and 5% were ambivalent, or refused to answer...).  This number is quite increased from 10 years ago.  Has anyone ever calculated future percentages, based on the trend?  Anyone good at graphs????

[Recusant]

Christianity has been obsolete since the Enlightenment at least, and that's being very generous.  As for when Christianity might become the minority position in the US, that's a lot tougher to answer, since societies don't follow easily mathematically modelled trends for such intangibles as religious belief.  Population and migration are more amenable to such treatment.  If we ignore this reality, then by looking at the American Religious Identification Survey (PDF) report, we see a drop from 86% of Americans reporting themselves as Christian in 1990 to 76% in 2008.  That's a little over an 11% drop in about 20 years.* So if we foolishly say that this trend will continue to follow the same rate, then in another 20 years or so, we would see the percentage of Christians in the US at a little under 68%.  Another 20 years, we would see the percentage at around 60%.  Another 20 years, we would see the percentage at a bit over 53%.  And in another 20 something like 47%.  That puts us somewhere near the year 2090.  I would put absolutely no faith in these calculations because of the sociological reality that I mentioned above, but also because I'm not a great mathematician either.

* Note that 10 is around 11% of 86. So though the drop was 10 percentage points, it was actually an approximately 11% drop.

I decided to try out a graph-making site just to see how it worked:

 

(Edited to add graph)

[Tank]

The problem with extrapolation (taking a few points on a line and extending the line) is that the conditions one is extrapolating into must be very well  understood. In this case that can't be guaranteed thus it is not practical to carry out an extrapolation. One variable could be certainty of belief. The existing de-conversion rate is probably among the least certain. As the de-conversions happen the remaining theists have a higher average certainty of belief and are thus less likely to de-convert. Unless one can accurately correlate the probability of de-conversion verses the 'certainty of belief' one can not make a meaningful extrapolation. And that is just one factor. There may be other factors at play, age for example. Are younger people more likely to de-convert than older people? Location, are people in the North more likely to de-convert than in the South?

There may also be a tipping point. It could be that for theism to hold a dominant position there has to be a minimum percentage of theists within the society. For arguments sake lets take an arbitrary figure of 62%. Once the percentage of believers drops below that value the number de-converting rapidly increases as the particular ideology no longer has the critical mass required to sustain itself. Thus it may look like it could take 50 years for Christianity to fall in the minority, but the tipping point could be only 5 years away and once that point is reached the collapse to a minority position could happen in another 5 years. There may also be a hard core of believers that will never de-convert and will die still holding their beliefs.

[terranus]

Sure, I can tell you exactly when that will happen. In about 100 years, after some pretty significant scientific advances, and after the U.S. disjoins the South from the union.

[KDbeads]

Sure, I can tell you exactly when that will happen. In about 100 years, after some pretty significant scientific advances, and after the U.S. disjoins the South from the union.

Uh, you are not leaving me down here with these nuts I refuse to be alone with them.

[periwinklefish]

Interesting graph, thanks for taking the time.  I'm wondering if there is a European (or another country currently more atheistic) model that could be used as a template...  although the fundamentals in the US probably skew things a bit...

[terranus]

Sure, I can tell you exactly when that will happen. In about 100 years, after some pretty significant scientific advances, and after the U.S. disjoins the South from the union.

Uh, you are not leaving me down here with these nuts