It is a matter of Identity.

When One dwells in Unity Consciousness, Oneness Consciousness, Christ Consciousness, where is the "other"? If there is an "other" it exists because I, as the creator of my own reality, have made it so. I have a choice. 

One realizes, (makes real) that which is identified with, therefore, within choice there is Duality which manifests out of the ONE.

When it was said, Love thy neighbor as thyself, doesn't that guide towards awakening into Unity Consciousness? If I love "you", am I actually loving my Self? If I harm "you", am I actually harming my Self?

The level of unity awareness one expresses/dwells within is manifest according to that awareness. 

Blessings to us all!