I just read an answer on this sub that mentioned in passing that only 15-20% of Americans in Washington's time belonged to a church and attended at least once a year. I would have imagined church was a far more central part of most American's lives at that time.

My sense is that religiousity is far higher than that nowadays, even after decades of decline: an quick google brought up this article stating church attendance is down to 50% from 70% in the 1990s. (https://news.gallup.com/poll/248837/church-membership-down-sharply-past-two-decades.aspx)

I'll admit that in my ignorance I always assumed nearly everyone was religious (except deviants and philosophers) until people started to have access to public schools, rock-and-roll music and birth control in the mid 20th century.

So when, exactly did Americans get so religious? What caused churches to take over American social life and when did religiousity and church membership peak?

I'm Canadian, so I would be interested to hear the answers to these questions as they relate to British North America/Canada as well.