However, the graph presented by no means entails that Protestants are becoming atheists more than Catholics are. In fact, it could be that Catholics are significantly more likely to turn atheist than Protestants are.
Suppose Catholics have many more children than Protestants. If those Catholic children are more likely to eventualy become atheists than Protestants are, it could produce a graph such as the one shown—a flat line for Catholicism (which experiences strong positive and negative changes, from the kids and deconversions), and a rising line for atheism.
As for Protestantism, even if the decrease is explained totally by flights to atheism, the magnitude of Catholic apostasy could just outstrip that of Protestant apostasy. As long as Catholic fertility matches Catholic apostasy, the graph will not change.
I haven’t looked at the study.
However, the graph presented by no means entails that Protestants are becoming atheists more than Catholics are. In fact, it could be that Catholics are significantly more likely to turn atheist than Protestants are.
Suppose Catholics have many more children than Protestants. If those Catholic children are more likely to eventualy become atheists than Protestants are, it could produce a graph such as the one shown—a flat line for Catholicism (which experiences strong positive and negative changes, from the kids and deconversions), and a rising line for atheism.
As for Protestantism, even if the decrease is explained totally by flights to atheism, the magnitude of Catholic apostasy could just outstrip that of Protestant apostasy. As long as Catholic fertility matches Catholic apostasy, the graph will not change.
Catholic and Protestant birth rates have converged in the US.
Fair enough.