Where there is no evidence for, nor against, a notion, then we don't know, we can't know, we don't have enough information to know.
In order for you to be able to say that your claim "Where there is no evidence for...a notion..we don't have enough information to know" is something you can say you 'know', you'll need to provide evidence - by your own epistemological standards.
This would bring us to a second test for false religions: inherent logical contradictions, and logical fallacies within a specific belief should also render that specific belief suspect at best, or false at worse, and likewise any religion that depends on one or more logically invalid beliefs, beliefs that have been invalidated by self contradiction or that are logical fallacies, is suspect at best, or false itself at worse (to the degree it is based on false beliefs).
So a religion that has a deity that doesn't get involved in the universe, does not provide any revelations yet is still the cause of some religious experiences would count as 'suspect at best'?