Supposing that God exists, supposing that nothing can be created out of nothing, then the world must be created out of God. That is the world is not apart from God.
Famously Spinoza argues that the World was in God. Does he use some species of the argument above?
But traditionally one speaks of God being the unique self-subsistent & neccessary substance - substance being a technical Aristotelian term. Is then world then made of Gods substance? But in particular Spinoza argued that the world was part of God in two attributes - of thought and of extension.