The question is about the word "youths," not "youth" nor "young," nor is it about being young.
My first thought was that there is no negative connotation to "youths," but on further reflection, it is youth that does not have either a negative or a positive connotation -- but "youths" does indeed have a negative connotation. I suppose this is because "youth" could refer to any young person, some of whom are actually good! Whereas "youths" applies to a specific group of young people, and we all know they're up to no good when they form into groups, right? Drunken, disaffected, etc. Perhaps the young people of your church could be encouraged to reclaim the word "youths" by applying it to themselves.
I hadn't thought about this before, so your question is appreciated.