The other day I was at my friend's house who are not believers. I tell them, on and off, stories from The Bible and about Jesus. One day 11 year old boy in the family asked me that how can we be sure that the authors of books in The Bible were not Schizophreniacs and how did they know that God was dictating them. I tried my best to show him how the books from Genesis to Revelation are all connected though they were written in different ages over a span of more than thousand years, but he was still not moving away from his thought of Schizophrenia.
Any other ideas how to give him the message about writings inspired by God?