The illusion of separation is Self-engineered.

What do you want me to tell you? I'm not going to lie. Of course, we are all One but there's more. One Self Itself Is. One Self experiences itself as the sum total of its own reality; reality is One Self.  This One Self is that which is G-d. Yes, it is true, separation is an illusion alright. The illusion of separation is Self-engineered; all is Oneself. We, Oneself, have staged all this (illusory separation nonsense) just to be able to love. There's nothing new under the sun (or should I say son) for after all the son is the father made manifest, it is Oneself materialized. That which is, is I. I is all that is as One for it is; I is all of you as One for you are. Don't you remember? The only purpose is Love!
~ Wald Wassermann