Ariel talks about how in order for one to know what love is, they must be in love. Similarly, in order to know spiritual truth, it too must be directly experienced. The great thing is that we all have an inner guru which allows us to know truth for ourselves, regardless of what we have studied beforehand. Your beliefs may affect what knowingness you have access to, but they don't really determine what is ultimately true. The knowingness is found in silence, hence the statement, "be still and know."