Seems to me there have always been people "going through the motions" that never had any faith at all, all around us. If we had the same tools during the 1700s, we probably would have found the same proportions or worse among everyone at that time.
We simply have to a better job of getting the faith to everyone.
I lived in Britain in the mid-80’s. It was quite a-religious back then. I chalked it up to the fact that it is a Socialist country. Even then, in most circles, if you were religious, you were perceived as stupid. I tried going to church there but it was just depressing.......I would sit in a stone church, constructed in the 1400’s, with one other person and the minister up front. The ‘enlightened’ ones all made fun of anyone who had faith.