Lord, I'm one
Lord, I'm two
Lord, I'm three
Lord, I'm four
Lord, I'm five hundred miles away from home
Who told you that only The True God can make prophesy? Some of those old prophets in whose interest it was to promote such ideas? Why would you believe they are speaking for God when their predictions are about as accurate as the I-Ching guy and his 56 "accurate" prophesies. Was he speaking for The True God? Funny how he wasn't even a Christian, though. How'd that come to pass?
Prophesies are post-diction. The only reason that all prophets are ancient is that there are enough millennia between us and them that there are no contemporary accounts available and the believers can interpret (post-diction, again) things that have happened so that they fit into the prophesies.
Have you considered that it's not a question of the true or false god or gods, but a question of your own arrogance in thinking that God, The True God, would speak through you. Is one not supposed to be humble before the Lord?
And didn't Jesus cleanse us of our sins? Why is The True God of the O.T. in all his vengeful and wrathful might coming back to visit you folks. Wouldn't The True God just wave his might appendages and do away with war, famine, suffering and inequity? Why does He have to nuke 2/3 of the world's population?