In fact, all that exists is God...
"One Universal Creator God. By The Grace Of The True Guru:
The actor stages the play,
playing the many characters in different costumes;
but when the play ends, he takes off the costumes,
and then he is one, and only one." (Sri Guru Granth Sahib Ji 736)
Meaning, that there is only the ONE in existence... we are all just the ONE creative consciousness (God), experiencing itself subjectively through many 'characters' (us) but when the play is over (this world ends), all that is left is the ONE. And in reality... all there ever was, was the ONE.
(sorry I don't know how to quote Gurmukhi like I have seen in other posts here)
Basically, quantum physics is showing us that matter arises out of consciousness, not the other way around, because a conscious observer is needed to create the physical world, at least the particles that make it up, since without a conscious observer, they do not exist in local space / time. Therefore consciousness can not be merely an emergent property of matter... There is an intrinsic connection between consciousness and matter...
“Wherever I look, I see the Lord pervading there, in the union of Shiva and Shakti, of consciousness and matter.” (Sri Guru Granth Sahib Ji 21)
String theory says that at the very basic level of the Universe, exists ONE pool of energy, from which all springs forth through creative consciousness. We are ALL part of that ONE.
As for who created God? From the Mool Mantra, we can see that God is 'self existent' and 'beyond birth and death' meaning that God was not created, nor will ever cease to exist, and exists through no outside force (self-existent).
I believe the illusion (Maya) is not so much this world itself (as we are co-creators of it, having the divine within us). I believe the true secret to 'Maya' and our attachment to it, is that we were never separate from Waheguru to begin with... we are always connected, always were connected, and always will be (going by the physics mentioned above being that ONE pure consciousness is the base of this reality) as all that is in existence and all that ever will be in existence is the ONE. The illusion that we are separate is what is hard to let go of. There is no 'US' there is only Waheguru...
---
As I am still learning much about Sikhism, I apologize for any mistakes in the above... just my interpretation.