"Divided" asks us to consider if contemporary youth ministry is biblical. It suggests that if we were to simply read Scripture, we would not come up with youth ministry as we currently experience it. It goes on to conclude that youth pastors and youth ministries are not biblically supported. Sounds interesting but is simply a straw man designed to support a premise while adding nothing legitimate to the discussion.
Is youth ministry biblical? The answer to that is clearly, "no." Does that mean that youth ministry is condemned or forbidden by Scripture? The answer to that question is also, "no." The question is unfair and misleading. There are many things that we do that aren't specifically prescribed by Scripture but appropriately carry out Scriptural principles.
Consider for a moment the number of things that "aren't biblical" that we accept without question. Cars, shoes, organs, sound systems, pews, pulpits, modern order of worship, incorporation, southern gospel music, contemporary Christian music, altar benches, etc. are all "unbiblical." Scripture doesn't mention any of these but, that doesn't make them wrong.
Scripture makes no reference to church structures. It is our responsibility to honor biblical principles while developing structures that implement the principles. The church has struggled throughout history with these issues. There was a time that Christmas carols, quartet music, organ music, and many other kinds of things were forbidden by the church. We've made dress codes and worship styles to be matters of biblical mandate, when they aren't at all.
Youth ministry is a structure. Structures need to honor Scripture. Arguing that Scripture doesn't mention youth ministry or youth pastors is irrelevant to this discussion. Scripture doesn't use the term "trinity" or "rapture," for that matter. I guess we'll have to throw those out, too!
Is youth ministry biblical? In regard to structure, it's an irrelevant and misleading question. The better question to ask is, how can we better fulfill our biblical mandate to make disciples. All ministries need to be subject to that evaluation.