First of all: Why do you assume that the universe was created- that something did come out of nothing? It's at least as plausible that the universe has always existed. Some interesting lines of current scientific inquiry that seem to point in that direction:
http://www.scientificamerican.com/article/rainbow-gravity-universe-beginning/
http://www.scientificamerican.com/article/2-futures-can-explain-time-s-mysterious-past/
Secondly: The 'God of the Gaps' is an exceptionally poor argument for the intellectual viability of religious belief. Just because science can't explain some phenomenon now doesn't mean that will always be the case. Rather than resorting to supernatural pseudo-explanations, it's much more rational (and intellectually honest) to say that we simply don't know the answers to certain questions, but we're working on them.
To return to the question posed by the OP....
I think another relevant issue here is the nature of scientific truth. Science gives us models which approximate the behaviour of some element(s) of reality as we apprehend it. All scientific theories are falsifiable, and science as an enterprise encourages, indeed depends on, attempts to falsify them. All scientific disciplines are subject to revolutions/ paradigm shifts. And historically, major disciplines have had their underlying assumptions radically revised by new theoretical insights- Biology by Evolution and then Genetics; Physics by Relativity and QM; Geology by Plate Tectonics; Psycholgy by the 'Cognitive Revolution' of the 1950s-60s.
Religion, by contrast, purports to offer something very different- access to absolute knowledge. The Bible/ Torah/ Qur'an/ Vedas/ whatever are claimed to be perfect knowledge, divinely given. They're also, of course, much easier to understand than science (see my point 3 above). So the choice that people have is:
- Believe in truth that makes no claim to absolute certainty, is frequently revised, and is bloody hard to understand.
or
- Believe in truth which comes from God, represents absolute certainty, is eternal and not subject to revision, and is completely comprehensible.
Unsurprisingly, many choose the second option.