if you 'believe' that substance can create itself......
then substance is God
there are 'beliefs' for that
I believe God is Spirit
and substance cannot beget Spirit
so....Spirit First
God as Creator
substance as creation
Actually I was being sarcastic...
If you want to presume God then who/what created God?
There are two possibilities, I'm sure there are many more, that I can think of.
One, the universe has always existed, in one form or another so there is no need for a first cause.
Second, The universe becomes "God". Intelligent life absorbs all energy/resources until it becomes one singular entity. You are a billion cell all coming together to create a single conscious entity. Even now we share our conscious thoughts across the world. Slowly man will become one conscious entity. This conscious absorption will continue until it encompasses the entire universe and becomes a singularity.
This singular conscious entity, "God" will then expand into a new universe destroying itself in the process starting the cycle over again.
So in the second case, God doesn't exist, yet.