If Baal came down to Earth in a fashion that would be unmistakable, I'd presume he existed. First, he'd have to prove he truly was Baal. Second, I'd have to know for a fact this isn't some sort of mass hysteria delusion. It's happened before. Third, I'd have to convince myself somebody isn't just screwing with me (who knows, this could just be some mass prank by some superior alien species). If the only other option is to perceive this as a test by Yahweh, I'd have to be convinced Yahweh exists. Then again, Yahweh isn't really known for being a very direct deity. What would be really interesting is if they both came down at the same time and tried to say the other didn't exist. Let's let that one wrap around our heads. This whole "test" thing is ridiculous because if it really is a test, all it proves is undying loyalty in the face of reason, which is all-in-all a poor excuse for belief.
God had prophets to write the bible, and you would feel they were lying to you. Satin has his people out there to not to have people believe in the bible or in god or even Jesus Christ, Has to be by faith to. Look around you and see what god has created for us.
I would wonder why he would do a good act and then convince me that God doesn't exist when in fact why would it matter anyways, its a good act, why get recognition for something you wanted to do in the first place? I make my own rules and that's not for anyone to tell me what is correct and what is not. How do I know that that's not his own belief, because if he existed then other things must exist too so that statement would make no sense being as they are both spiritual beings. And why would a good act lead to a religious debate in the first place, it shouldn't, it should be because you wanted to not the other way around.