They start with the observation that people claiming no religious affiliation constitute the fastest growing religious minority in many countries throughout the world. Americans without religious affiliation comprise the only religious group growing in all 50 states. They claim their model predicts that for societies in which the perceived utility of not adhering is greater than the utility of adhering, religion will be driven toward extinction.
It is not hard to believe that this could apply to some of the better-known secular countries such as The Netherlands, but it seems more surprising that the trend in Ireland indicates that it is going the same way.
Meanwhile, during a lunchtime discussion with two Portuguese colleagues recently, they assured me that Portugal is a Catholic country, but that it hardly mattered as they largely ignored the teachings of the church. I had to disagree about whether it mattered, but that news is not altogether discouraging.
Here is a link to their paper. Sadly it fails to pass the 'two equation test' and reminds me that I earned my physics degree in spite of my lack of expertise in statistical mechanics!