“Why would [an evil spirit] write a book like the bible?”
Well, depending on circumstances, there are several possibilities. Now, most non-christians will say that the bible is the work of people. And that is certainly a possibility. But I do not rule out the possibility that spiritual beings exist. Hezekiah assumes that an evil spirit wrote the bible (or a book like it) and wants to know shy that might be. I shall give some possibilities.
One possibility is to create discord and strife among us humans. The bible has certainly done that. History is litterred with religious wars. An evil spirit who wants nothing more than to see an increase in human sufferring would have a motive to write many variations similar to the bible (but slightly different) to stir up wars.
A second possibility is that the evil spirit wants to get people to turn to one of its representatives as “lord and savior.” If people enter the spirit world as free spirits unless they voluntarilly make themselves bound, an evil spirit would have an incentive to want them bound to itself. From what I’ve seen, those bound to christianity act as though they under the control of an evil spirit.
A third possibility is if there is a type of judgement based on the overall character of our actions. People who consider themselves “saved” are less incoined to work to become better people. Most people try to improve themselves so they become better people. But people completely beholden to the bible do not.
Those are the possibilities that I can think of at the moment. There may be others. Does anyone else care to help Hezekiah with some alternative possibilities?