You are correct to question it. I honestly have not looked into whether it is causality or just correlation. Based on my own observation, being from a historically catholic region: churchgoing has faded vastly in 30 years, state and public school is secular.

Obvously, you are going to have communities where religion is fostered and the culture preserved. I dont really see a problem in it though. We cant really expect it to go away, nor should we work towards forcing it to go away. An example may be pagan religions which were forcefuly brought down more than a thousand years ago, yet have not been rooted out even today as neo pagan variants are poping back up.