I have never really found a good definition of existence. If it means that which can be affirmed by our senses, then there are a great many things that our senses cannot directly affirm, but that do impact our awareness electricity and magnetism, for example. Do they exist? If not, then if they do not exist what are they, or does only whatever it is that causes them to happen exist (much like a collision between two cars)? Does the collision exist? If so, where does it go when the cars are immobilized?
This is the problem with words. They confuse us as much as they enlighten us. A good argument could be made that existence does not exist. It is a consequence, not an object or even a collection of objects.
To my mind God does not exist. It/He/She created existence
In fact, I believe historically we have come to view God from at least three different angles (perspectives that cannot possibly be reconciled with one another) simultaneously if our view is even close to being accurate. I call these perspectives God Without Us, God With Us, and God Within Us.
God Without Us doesn't care. It/He/She is Brahman in concept, not something we could possibly imagine, much less understand. This would be the creator God. This would be the God that created existence, whatever that is. This is the awesome God; the one that strikes fear into our hearts This is the God who would send us to Heaven or Hell arbitrarily (should Heaven or Hell exist) just on a whim
God With Us is the companion (compassionate) God. This is the God we talk to; the one we confide in (confess to). It/He/She is the one who forgives us for anything we feel we have done wrong. This is the personal God who cares for us so much It/She/He would give Its/Her/His life (if She/He/It were alive) to protect us from harm
God Within Us is a kind of spark, a kind of perfect (or perfectible) us. It/She/He is what we perceive as an inborn awareness of what is right and what is wrong, a kind of depersonalizing of ourselves to the extent that we interpret it as not us, but something within us guiding us; a kind of very personal mentor always with us and very judgmental though not necessarily vindictive.
All this speculation is, of course, ridiculous but it gets me through the day and it does confuse those who would convert me to their just as ridiculous delusions (God Fearing and Atheist Aggressive Evangelicals alike).