From The Message Bible:
Deuteronomy 18:20 "But any prophet who fakes it, who claims to speak in my name something I haven't commanded him to say, or speaks in the name of other gods, that prophet must die."
21 -22 You may be wondering among yourselves, "How can we tell the difference, whether it was God who spoke or not?" Here's how: If what the prophet spoke in God 's name doesn't happen, then obviously God wasn't behind it; the prophet made it up. Forget about him.
Uh Uh.
Sylvia