Insider testimony and evidence

Questions about how one person could trust another person on the topic of God, how STR obtained information about God that others haven’t obtained, and whether God only matters for the purpose of the afterlife.  

• How could one person trust another person on the topic of God, and how did you obtain information about God that I haven’t obtained?
• Aside from Heaven and Hell, does God matter? Atheists and Muslims experience the same world you do.