Hi,
You stated your philosophy succinctly, so I'll try to do the same! I agree that we are all lower-dimensional parts of the One who is all-encompassing and infinite. As human beings, we often do not see this, but view the parts (others we meet in the world) as discrete entities. This is what creates war and misery.
There are many ways to perceive this truth. One way I use is meditation on the yin yang, which shows that "this" is a part of "that" and vice versa.
However, I believe the harder we try to see the truth, the more difficulty we have. It can only become part of us when we let it go.