There comes a point in scientific analysis where the causes and affects which have lead to an occurance or state become unclear. Whether we ignore the subtleties of friction and wind or cannot comprehend the quantum movements of quarks and such.
Yet, just the same the lack of evidence to demonstrate the existence of a god is used as a reason to not believe in him/her/them.
However, since we don’t actually know what’s going on in the physical world, it cannot be used as evidence that god is not operating in it. There’s no proof of origination to complete the chain of events, nor even a complete chain in its self, to demonstrate a lack of god.
At the end of the day, it requires just as much faith to say that god does not operate within those things we do not understand as it does to say he does.