Pope Francis, LDS President Russel M. Nelson and convicted felon Brian David Mitchell all claim to speak for God. How we do know which, if any of them, is right?
The best we can do is look at what happens as a result of what they and other claimants say and do, and work backwards.
Mitchell, the self-styled prophet who used to wander the streets of Salt Lake City, kidnapped a young girl out of her own bedroom and spent months abusing, assaulting and otherwise terrorizing her. This is not the kind of behavior that most folks envision when they think of the almighty.