There are many reasons that many teenagers are rejecting God and the Bible. Many churches cannot defend a belief in the Bible.
Many teenagers take science classes and the teachers teach that Macro-evolution is true. And this idea can explain the natural world so the young person could reject the Bible.
Many twenty years old adults lose interest in their faith when confronted with supposed facts of evolution. While others will compromise and have doubt about the Bible.
Pastors, parents, students and Bible study leaders need to be ready to understand the attacks on the Bible and the scientific problems raised by schools and media. Gaining an understanding of the bare evidence in science gives Christians the opportunity to be a witness. But the knowledge of the Bible is important.
As Christians, we need to be able to have the right questions and have answers when confronted with false Biblical doctrine and science in the name of promoting evolution.