The thing is: God/Nature/Manitou/Chuck Norris gave us the universal language: mathematics. This is what physics are based on.
Science tests, measures, observes, and then constructs theories out of these observations and measurements by using mathematics, then makes predictions, tests, measures, observes again, and so forth... in an ongoing, possibly never ending cycle.
Spiritual experiences cannot be measured or observed, they cannot be tested, they cannot be repeated, and they cannot be described by the mathematical language. Hence they are completely irrelevant to science. Science doesn't care if they exist or not, because they have no influence on what science tries to describe.
This is an unproven philosophical position
Which is again a statement that is contradictory in itself. Philosophical positions can
never be proven, otherwise they would not be philosophical.