Canon Holmes of India who years ago said to most people God is an inference, not a reality. He is a deduction from evidence which they consider adequate, but he remains personally unknown to the individual.  He must be they say therefore we believe he is. 

Tozer  :The bible is a self-evident fact that men can know God with at least the same degree of immediacy as they know any other person or thing that comes within the field of experience.

(extract from Pursuit of God by Tozer)