Unknown: I disagree. Consider this definition: "An ontologically fundamental unique entity that has, in some sense something resembling desire/will, further, this entity deliberately, as an act of will, created the reality we experience."

Further, barring the case of, say, a deists, additional things could be noted: "An entity that in some sense directly orchestrates all of reality, even though it may seem otherwise."

I'm pretty sure most theists (at least monotheists) would agree that this is the thing they believe in, no?

So no, I don't think the disagreement between atheists and theists can be properly represented as a definitional dispute.