Okay, so in your opinion he’s not a liar.
He just never went to a book store EVER. Never had a Christian friend. Never went into a Church, or rectory, or library or school, or anywhere else a Bible might be in 20th century America.
And how likely does that sound to you?
I have no idea except that I know him well enough to know he is no liar. Beyond that, I have no idea why he had never been exposed to a Bible. I will ask him sometime.