[MrLeRoy]

attendance levels at Mass now are about what they were a century ago (high attendance levels in the decades before 1960 were the anomaly)

The second clause does not follow from the first; you'd have to study attendance levels over a few centuries to determine what is the norm. And even if high attendance levels in the decades before 1960 were the anomaly, it in no way follows that those high attendance levels were a causeless fluke whose end was also causeless.

[ClearCase_guy]

Indeed. And the way this is written leaves open to interpretation how they are defining "attendance". Is it number of Catholics attending Mass each week? Is it percentage of Catholics who attend Mass each week? Due to population increases, raw numbers being equivalent over a 100 year period is really a decline.

Also, there is the possibility that Catholicism was heading toward a significant upswing prior to the 1960's. With "attendance" levels being much higher than they had been 60 years before, things were looking good for the Church of St Peter. But something came along to reverse that trend, and send the attendance levels back down to their previous levels. Wonder what?