Not OP, but IIRC Jonathan Edwards held that the whole universe existed in the mind of God.

This is functionally indistinguishable from the "perfect simulation" hypothesis.

That was what leapt immediately to mind the first time I encountered the Simulation Hypothesis, as one raised on Christian theology.

A lot of the concepts about simulation and related things, are in Godel, Escher, Bach by Douglas R. Hofstadter, although it doesn't go into theology much, though there are headings like "Articles of Reductionist Faith".