The fact that people have religious experiences is interesting from the psychological point of view, but it does not in any way imply that there is such a thing as religious knowledge...Unless he can formulate this 'knowledge' in propositions that are empirically verifiable, we may be sure that he is deceiving himself.
Theism is so confused and the sentences in which "God" appears so incoherent and so incapable of verifiability or falsifiability that to speak of belief or unbelief, faith or unfaith, is logically impossible.
If the assertion that there is a god is nonsensical, then the atheist's assertion that there is no god is equally nonsensical, since it is only a significant proposition that can be significantly contradicted.
To make our position clearer, we may formulate it in another way. Let us call a proposition which records an actual or possible observation an experiential proposition. Then we may say that it is the mark of a genuine factual proposition, not that it should be equivalent to an experiential proposition, or any finite number of experiential propositions, but simply that some experiential propositions can be deduced from it in conjunction with certain other premises without being deducible from those other premises alone.