Oneness means that everything that exists is one by being connected to each other. Everything that is and ever will be created is created by the same Source that all is part of. We live in a world of duality and therefore we tend to judge and label into opposites like good, bad, light, dark, etc. It is our mind that separates. Without light there is no shadow. Without knowing what dark really is, we will never get to know the light. We need to experience both to find balance.
It is our mind and our fears that classify certain energies as enemies and want to attack them. But all play their part in the collective and all are part of the same Source. The Universe (Creator or G .O.D) is the Generator, the Operator and the Destroyer. These are all natural processes and these are all great teachers in our lives. The Creator exists in everything, the good and the bad, the dark and the light. 
In Shamanic healing, the foundation is that everything has Spirit and is part of Great Spirit; which is the Spirit that moves through all that exists. From this understanding, everything is always taken care of with love and respect. The Shaman is the weaver of the web; The web of Oneness. It is woven with love and understanding.