When you study the Bible record, the nation of ancient Israel, how the Bible was put together, and the many things the Bible talks about, you will see that the Bible is truth.
Did you visit Israel yourself or only study acient Israel online and library?
Probably he just read it online or maybe with some books on the library under fictional books section and just alledgedly thinking that it was automatically true. He didn't even support his argument with something that's seem to be a viable reason.