I've not read much Jung as he never appealed to me since I find there to be something of the fraud about him. Another person who wanted spirituality without God. But I've read books by people influenced by him, and one of the ideas that seemed to take hold at one time was that you have to integrate your dark side with your light side to reach a state of wholeness. This is, to put it bluntly, nonsense, maybe even satanic nonsense.
Whether Jung really said this or whether it is a misinterpretation of things he might have said, I'm not sure, but the idea is out there and it needs refuting. It's linked to the possibly Gnostic idea that Lucifer is Christ's dark twin, in an ultimate sense working with him to drive evolution onwards. Another shot that misses the target and tries to justify evil, even if it might have a spurious sort of almost plausibility.
Good is good and evil is evil and there can be no alliance between them. That doesn't mean that God cannot bring good, and maybe even greater good, out of evil but that is a very different thing to saying it is part of his plan and can somehow be accommodated. Evil must be overcome not integrated either outwardly in the world or, especially, inwardly in oneself. The misconception arises I think because of a confusion between evil and nature. The natural is integrated with the spiritual, not rejected but perfected by grace, but evil, darkness, must be overcome by light.
Here we have the clue to the resolution of this problem. Light does not integrate darkness but obliterates it. There is no fuller state that comes from their union. Likewise, our dark side must be rejected by subjecting it to the light of Christ. On a psychological level you can say that vices contain, and can be transformed into, their opposite virtue, say aggression into heroism. But, on the spiritual level, vices must be overcome. There is no integration of dark with light. Evil, sin, must be eradicated not integrated.