Your argument is that it's possible for a human brain to manifest anything it wishes.......saves 2 things.
Miracles and prophecies
And try this,
O Lord, I am your faithful servant. It's you our Almighty God who commanded here for your will to be fulfilled. Please show us that it's your will that I am here as commanded.
Well, you shall see how the Red Sea depart. Hehe...
When you question how others' brain work. You forget that your own brain is also limited. It's very easy that our thoughts are limited to our own concept of time and space, limited enough that we fail to speculate that a communication channel between God and man can be established through prophecies and miracles.
So please try to speculate more about why the topic "prophets" are always closely connected to prophecies and miracles. That's probably the way how they "talk" beyond the "brain delusions" as you suggested.
After that, you may start to speculate why miracles and prophecies but not your mobile phone are used as a media/platform for the communication.
