A lot of 19-year olds have no idea what they want to do with the rest of their lives - I know I didn't @ that age. Typically, most people of post-H.S. age are either working and/or in college. I know JJ had gone to college, but was taking some time off & was working, etc. It's very possible he didn't know what he really wanted to do re: a career, etc.
I also don't believe that someone at the church attacked Jason over the denial of joining a seminary; that seems way too out-there. If anything, it'd be more likely that him being forced into this would lead more to a suicide or running away.
I know you're not suggesting that this is probably what happened here, but just to address this (since it's been brought up before, possibly on a previous thread): I've been following this case since I first heard about it last summer. And, I never thought that JJ "ran away" due to pressure from his family. If he had, I'm convinced he wouldn't have done it under the circumstances that occurred. I.e.:
1) Vanishing on the way to work when he was called in unexpectedly - while a co-worker (who was doing him a favor) went out of her way to pick him up. I.e., the whole situation re: his going into work early was unplanned.
2) Plus, he was walking on foot - while his car was in the shop.
3) Also, as has been said - there was 0 activity on his financial/bank accounts after he vanished.
So, he left town without his car, on foot - and without touching the money (admittedly not much) in his bank account. Then, he never contacted his family in the 21 1/2 years since he vanished - to at least let them know he was OK, etc. I find this extremely unlikely.
And, if he had decided to end things himself (which I don't believe either), I don't see why the body wouldn't have been found by now.