It depends on what you mean by "determine".
Some time ago, FatyCatty provided me a link to a page where I found a good example of what I want to get across. The text used the example to express something different. The message came across as something similar to "don't mess with untestable hypotheses, we can't waste our scientific resources with these sort of ramblings; this is not the way to do science". But in fact, it was conveyed in a nicer way, so that it was also potentially persuasive to believers. So instead of saying "this is not the proper way to do science", it said something like "science can't do that". The reason why I interpret it this way is the actual example, which seemed intentionally ridiculous, and was as follows:
Consider the fanciful idea that gravity is caused by undetectable, supernatural gnomes connecting everything in the universe together with invisible chewing gum.
The text said afterwards that science can't study that explanation since it's supernatural.
Which is very nicely put, but not entirely true. In fact, it's not the condition of something being supernatural, but the absence of evidence, what prevents science from investigating anything. That's exactly the process by which the supernatural has become part of the natural world: we just found evidence of the causes of what we called supernatural phenomena. Also, scientific resources aren't devoted to discover the inexistence of things, because that would be a literally infinite waste of time. The praxis of the scientific method and a consistently applied epistemology is that, in absence of evidence, this hypothesis is not reasonable because it doesn't explain anything that isn't already explained with lesser assumptions.
We cannot absolutely justify that the idea that these supernatural gnomes connect everything together in the universe with invisible chewing gum is wrong, nor that we aren't connected to the Matrix. Of course not. But we do know (not "absolutely know", because in that sense the verb "to know" would be almost entirely useless) that these ideas are not true.
God? Yeah, of course you can entertain the idea that it might exist, but it's not even a reasonable hypothesis. I claim to know that God doesn't exist. Gods are myths and totally unnecessary and superflous to explain the universe. I could be wrong, but I also could be wrong in assuming that I'm a human being, that the universe I perceive is real or that invisible gnomes cause gravity by chewing gum. The number of theoretically superfluous things that could exist would be infinite, and I don't see a reason to give the concept of God a special treatment.