Before I dive into my point let me make one thing crystal clear, I believe that the family should be the number one influence on the spiritual development of our children and teenagers. Deuteronomy 6:4-9 was written to the moms and dads of Israel in the Old Testament and is a powerful reminder to all of us moms and dads in the New Testament that spiritual development starts in the home.
If the teenagers in your church have believing parents it's on them to "bring them up in the training and instruction of the Lord" (Ephesians 6:4.) We, as parents, should never delegate this sacred duty to a 25 year old youth leader straight out of seminary. In a perfect world, parents would work in conjunction with youth leaders to build teenagers who are fully committed to and maturing in Christ.
But we don't live in a perfect world.