Question on quantum computing and many-worlds interpretations of Quantum Mechanics

This is possibly a naive question that occurred to me, which might be down
to my limited knowledge of the subject.

The possibility has been raised on the list of the idea of quantum computing
being able to solve problems such as factorization of very large numbers,
that could not be done on a conventional computer because of the numbers of
calculations required. The success of a quantum device therefore
necessitates the existence of parallel universes ( multiverses ) in order
for all the computations to be carried out in parallel.

This in turn raised worries of a theological nature. If such devices proved
the existence of multiple universes, then what were the theological
implications - if a universe existed in which Iain Strachan were not saved
(or as many in which I was saved as in which I wasn't saved, and a great
many in which I didn't exist at all!) , then what would be the meaning of my
faith, or indeed the lack of faith of the atheist version of me in another
universe.

It seems to me (but it may be because I don't really understand quantum
computing) that there is a fallacy in this argument. In order for a quantum
computing device to perform the huge number of parallel calculations, it
must of necessity exist in all the parallel universes that are involved in
the calculation. Furthermore, if we recall the principle that the flap of a
butterfly's wings can (by chaos theory) "cause" tornadoes the other side of
the world, then it would seem to me that the other universes in which that
quantum computing device sat in the same point and had the "go" button
pressed by the same person at the same time, must all share precisely the
same history as the one we're in now. Whoever was saved in the one must be
saved in all of them, because the slightest deviation would cause divergence
of the behaviour of the system.

Maybe this is too simplistic a view? Can someone enlighten me?

Iain

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After the game, the King and the pawn go back in the same box.
- Italian Proverb
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