So most youths I know wouldn't want to be known as the holy-of-holies. How then do we make serious theology accessible to Christian youths without involving them going to "schools" or "seminars"?

Before we start thinking about involving a theological curriculum in our weekly youth services, I would suggest that we start in our cellgroups. The cellgroup leader could ask questions pertaining to our faith, such as "Why does a good God allow evil and suffering?" or "What happens to unevangelized unbelievers?"

These are very deep and challenging questions to many Christians, youths included. And they require answers. Now, they don't have to be absolutely convincing. But they ought to be reasonable. The CG leader could then give out some answers and also ask them to think about it, and send them searching for more detailed answers of this own. (We also ought to point to a place where they could start, not only in the Bible, but to books and websites which they can refer to.)