The devil’s bible would look christian but deny aspects of the faith that leave simple humans crippled in the spiritual sense. They would then be easy prey for the devil and his minions.
This bible would have to be cleverly disguised and include most accepted books. Some could be altered. It would have to be created in a period of crisis to lend it’s development credibility. It would have to be so close to the real bible that people would be fooled for hundreds of years.
Perfect…
Wait a minute, who let it go with that number of books - 66!