One would think Darwin and outrageous claims of miracles would tell people religion is not for them. Churches and those with no church are looking for a single variable that is driving young people from the churches of their births. They are leaving all churches.
A variable some sociologists find important is living with someone out of wedlock. It sets the stage for permanently leaving the faith. I never would have thought that was such a big issue. On the other hand, next to announcing to one’s parents and church he/she is gay, cohabitation perhaps puts one across a stream from his/her previous values and it seems too far to swim back.
As the decades have gone by, young people in the U.S. have moved into a different dating pool. In my youth the other teens I knew were in my small circle, almost always part of my church life.
This has changed so the dating pool is much larger and more unlikely to be within the same religious circle. Living with someone of a different faith before marriage apparently sets the stage for many to not return to their church even if the never marry that early unmarried partner.
The age demographics of marriage also are pushing the change along. Marriage ages are averaging in the late 20’s. This has hurt the pattern of taking a break while young and returning to church after marriage and children.
The direction of social change is not predictable. But, we know the current trend.