I'm not sure who scares the tourists away from this site, but I have noticed that when I participate less, the forum gets more active. So, perhaps I'm the one who scares the tourists such as yourself away? I'll try to keep my responses limited...
In my opinion, the Christian universe (as I understand it) is not really a quantum mechanical one with respect to the fundamental ideas of superposition/ collapse of the wave function. Rather, the Christian universe seems to be a wholly deterministic one.
Ah! The decision of the individual with Christianity is supposed to be based on free will, and undecidable function that requires the person to actually make the decision to find out which way they will decide. There is no shorter algorithm to determine what a person will decide, hence it is undecidable and uncertain. Determinism is based on their being an algorithm in advance that would determine what a particle would do if given enough knowledge of the present state. Far from being deterministic, the Christian perspective of a free will is undecidable and uncertain.
In fact, Paul somewhat extended this notion to the future as being seen as through a darkly tinted glass. We see the general features of the evolutionary process, but we cannot make out the specifics. This could be seen as support for the uncertainty and indeterministic nature of the universe (at least our knowledge of it).
Having said that, from my own (agnostic) point of view, I see God as being in a superposition between existing and not existing, and that one's belief will collapse the wavefunction into one of those two realities for each individual.
Well, I think Christianity extends the idea of superposition to the entire universe by stating that the former heavens and former earth pass away, and there is a new heavens and new earth. This, I suppose, it could be wildly interpreted, that the whole universe is in a superposition state of old and new, with the 'new' state being the state after a measurement (judgement), and reality eternally fixed in this new state. One could even contend that the probability of reaching that state is overwhelmingly one such that reaching that final state is inevitable (such probabilities do, I believe, exist in quantum mechanics).
As for God existing and not existing, such as in being in a superposition state, it's an interesting idea. Correct me if I'm wrong, but in quantum mechanics we don't say the wavefunction is both there and not there, right? We say that the wavefunction is 'there', it just doesn't necessarily have high probabilities of there being a strong field at that particular location. So, in that sense, it would be compatible with a Christian view that God can appear to abandon a situation such as when Jesus asked God while being crucified "my God, my God, why have you abandoned me?" Perhaps this statement is so much tied with what Jesus actually said that it was impossible for the New Testament writers to not include it in their testimony. A very powerful indication of how God (wavefunction of the universe?) can be missing at certain moments in life.
It's fun speculating and all. I wish I had a dollar that quantum mechanics was abused like this, but what the hell, nobody's reading this anyway (at least not more than a dozen of us). So, who cares.