Can you help me show reasons the bible may NOT be written by God?
Keep it simple and put the responsibility on them to prove that it was written by god. Perhaps you could ask a simple question like; "Why don't the miracles prove the Bible to be unreliable?"
Here are a few pointers I gave to Shining One some months ago, needless to say he didn't address any of them.
The physical impossibility of a man walking on water.
The chemical impossibility of turning water into wine.
The biological impossibility of three day old corpses being brought back to life.
The mathematical impossibility of the parts being greater than the whole (loaves & fishes). Let's look at this one.
(Matthew 14:19-21) . . . he commanded the crowds to recline on the grass and took the five loaves and two fishes, and, looking up to heaven, he said a blessing and, after breaking the loaves, he distributed them to the disciples, the disciples in turn to the crowds. 20So all ate and were satisfied, and they took up the surplus of fragments, twelve baskets full. 21 Yet those eating were about five thousand men, besides women and young children.
That is a mathematical impossibility. It is either an elaborate and complex hoax, which I doubt, or it never happened and is simply a lie which is what I strongly suspect.
Good Luck