The 'everything is a simulation' idea (ES for short) functions best as a thought experiment or stalking horse. The main argument for it is the probability one, which is flawed since it leads to an infinite regress. The argument from parsimony is more interesting but works just as well for idealism of the roughly Vedantic kind, it is like saying that what distinguishes reality (as maya) from a dream is that its fabulations are more persistent - and this persistence is nothing metaphysical, only the consequence of a multiple perspective, or what is sometimes called 'consensus reality'. ES casts an interesting light on monotheism. For example, to say that the merit of a simulation is that it not be boring raises the question of how we can know what its creator might regard as boring. The answer of course is that we can't; the creator's intention is inscrutable. If however our conscious understanding of who and what we are is of any significance to it then we would expect that some clues would be left lying around, and given the principle of parsimony this would be more likely to resemble revealed religion or mythology than direct intuition into its level of understanding. This again raises the question of what the significance of our understandings could be to such a creator. Are they in some sense the 'readouts'? Can the creator access anyone's experience via some sort of FPV? Or is it only looking at the progress of global parameters? ES would seem to require that the creator is subject to time in more or less the same form as we are. You can write down some simple equations or rules, quite transparent in formal space, but you don't know what results they can produce until you 'run' them and watch the results unfold. The God of theism is outside of time and hence omniscient, while the knowing of the ES creator is in time and hence limited, even if it is perspicuous relative to the current state of its world. Again, God is equally close to every created soul, while the ES creator, having a single perspective, can presumable only 'inhabit' one subjective 'read-out' at a time. That is, unless all minds in the simulation are unified on some higher level inaccessible to them individually. ES raises the question of a consciousness transcendent to our own but not Divine. Is that possible? Surely this possibility is one that haunts us in an essential way, as in the persistence of attempts to bring about 'global' consciousness.