For years, your GetReligionistas have been saying that the aging of mainline religion — first on the doctrinal left and now in many conservative traditions, as well — is one of the most important stories of our, well, age.

Look at it this way.

Stage I: In the 1970s and ‘80s, America’s liberal mainline Protestant churches went into what now appears to be a demographic death dive (hello Anglicans in Canada). This created a massive hole in the middle of the public square that led to …

Stage II: Evangelical Protestants rise to become the new “it” factor in American life and politics (see video at top of this post). Evangelicals are still a massive piece of the religion marketplace, but now…

Stage III: Evangelicals are starting to show signs of age and their demographic trends are mixed. Keep your eye on statistics linked to baptisms and converts to the faith. And look at the ages of all those people in the “nones” category.

This leads to this week’s fascinating chart from Ryan Burge of Religion In Public.

Read on.