That is, things exist in relation to each other. But if there is nothing other than god then either god cannot be said to exist for the reason just explained, or god is the known world, in which case, by definition, god is not a god. It is a principle for scientific labour which means that one should use a simple explanation with a few explanatory premises before a more complex one. Let's say that everything must be created, and that was done by an omnipotent god. This entity can surely be replaced by the known world.
Most theists agree that god has a nature.
God is not really an explanation, only a non-explanation. It is impossible to gain information from non-information so God as an explanation is a dead end. When we have said that the reason for something is that 'god did it that way' there is no way to understand it any further. We just shrug our shoulders and accept things as they are. To explain the unknown by god is only to explain how it happened, not why.