What reason do you have to believe him? What if he was lying?
I have no reason not to believe him. Of course, if in some future date, his actions disagreed with what he had said, then I'd change my mind. I'm working on two premises here:
1) We all think differently. My consciousness is different from yours. If I relate an inner experience, who are you to deny it. It was my experience. if I say I went to Chicago, and you say, "You're lying!" then I guess thee is no discussion.
This is just a bit like your basic first response to a stranger. Some people start with distrust, and learn trust. Others start with trust, and learn distrust.
2) My god is a loving God (Siva) so when God speaks to me, I just know that he wouldn't command me off to violence.