Ryan Burge is a sociologist who specializes in analyzing survey data related to religion. On one of his recent posts he discusses some data gleaned from asking "nones" (those who acknowledge no religious affiliation or belief) who grew up in a religious environment, why they left.
You can read his entire post here, but a couple of items that interested me - because they confirmed what I think most people already suspect - were that most nones who abandon religion do so between the ages of 15 and 25 and most of them had a father who was not religious.
The latter point is crucially important in a culture in which fatherlessness is so common and also because the importance of a father's example in a child's life simply cannot be overstated.
Here's a graph that Burge published showing the distribution of reasons "Nones" gave for leaving religion behind:
Notice how many chose religious hypocrisy, religion doesn't make sense, science, and lack of evidence as among the reasons why they left. This tells me that churches need to do a much better job of teaching their young people the reasons why their faith is far more reasonable than any secular alternative.
It's unfortunate that so many Christian young people, even among those who never walk away from the faith, reach adulthood without having gained a solid understanding of the basis of the Christian faith. It's as if the church expects kids to somehow absorb that understanding osmotically just by sitting in a pew.
With all the resources that are available to churches today on the internet and elsewhere this is really an inexcusable failing.