I think it's strange to say that people cannot know God. There are people who have had strong inner revelations and callings. If you have an experience of an inner ultimate spiritual authority that will change the course of your life, then who are we to say that this wasn't God?
Of course some will always say that it was just imagination. But if this "imagination" had that strong impact on you, labelling it like that is not gonna change the basic fact of the experience.