"Just so, I tell you, there will be more joy in heaven over one sinner who repents than over ninety-nine righteous persons who need no repentance."
I like verses about joy but have a hard time understanding the metaphysical interpretation behind verses about sinning and repenting.
It's amazing how Jesus can pack a great depth of meaning into a simple statement. The challenge, of course, then becomes to unpack that meaning for ourselves. The underlying Truth here, I think, is that we, as beings of Spirit, are not in human form simply to live within proscribed rules and boundaries. That's fine if that's what we choose, but our real purpose is to make spiritually inefficient choices, to learn from those choices, and to make better choices going forward. So "sin" is making those choices and "repentance" (from the Latin for "think") is to decide on another choice. There is "more joy in heaven" because we are fulfilling our spiritual purpose of learning to make the choices that will create the new consciousness Jesus calls the kingdom of heaven.