I have come to firmly believe that that the primary difference between teens who lived out their faith beyond college and those who didn't is when teens serve alongside their parent.
This doesn't diminish the need to teach and talk about faith with them. But is probably most connected to a parent who is living out their faith and doing it with their teen. The Sum of your life is more valuable than the words you say. Parents and adults -- live out your faith with your teens if you want to see them continue in the faith.