101:2.16

Religion must ever be its own critic and judge; it can never be observed, much less understood, from the outside. Your only assurance of a personal God consists in your own insight as to your belief in, and experience with, things spiritual. To all of your fellows who have had a similar experience, no argument about the personality or reality of God is necessary, while to all other men who are not thus sure of God no possible argument could ever be truly convincing.