If you don't know you should say so and I, or another Christian freeper, will explain it to you. If you do know then say so.
The subtitle of this thread, “why Christianity is losing the younger generation”, is neatly answered in your reply.
Further to the point, Christianity is not losing the younger generation; it’s only your particular brand of non-denominational, evangelical, literal, fundamental, I’m-in-and-you’re-not, cultish twisting of the basic faith that is.