I mean could God not simply be another name for the idea that the entire universe or multiverse is one?
Well in one form or another, that's the issue at hand. You're not really saying anything
If you take this position, what you're doing linguistically or philologically speaking is assigning a word to what you cannot comprehend.
Maybe that helps a person psychologically - putting a word to something, even when not comprehended, adds a level of comfort to us - perhaps because that act fools us into thinking it is comprehended. There are psychological studies on this stuff.
Ontologically however, when seeking some kind of truth or the limits of what we can know, this doesn't help at all. The 'truth' of it is tautological.
So, no it doesn't mean its wrong. It doesn't even mean we should stop talking about it. It just means to be careful with what we state is likely or 'true'. It also means we can't know anything about it, any more that you can tell me I'm wrong that various drafts in my garage are due to an invisible and (mostly) intangible dragon (someone used sort of this analogy before, but I can't remember who). You may be able to adjudge that pantheism is more likely to be true than the dragon in my garage, but I think they are analogous in that you can't prove or disprove either.
I think we have to be careful about the use of 'fancy' language surrounding something. Like behaviourism, which sought to qualify (quantify?) behavior scientifically , but turns out what's observed cannot be falsified. You're just observing and writing down what happens, which is fine if simple observation/documentation is your science.
But behaviourism (in this sense - I don't wholesale condemn it) and other such nonsense, purports to explain rather than report. That's where it goes off the rails scientifically. I think Spinoza falls under this as well..Maybe, very difficult to know what a lot of his writing exactly means.