If you have an inerrant code to work from, then you gain two benefits. Firstly, you do not have to make any effort or think about any issues, address any moral questions, or find the strength to live with uncertainties. It is the ultimate, lazy and cowardly, get-out.

While secondly, if you pick as your inerrant source a book, which is mixed up and ambiguous, complex and compiled from the writings of hundreds of authors, over centuries, then you can find in it justification for anything you want to believe just by picking the bits you want, or interpreting them. Yet you can then however claim that whatever you wish, has far greater authority than anyone else's opinion, because it is backed by an inerrant source, perhaps directly from god.

You may notice that these two are in complete contradiction, and the second is not even logical anyway.

But if you take a book which tells everyone they are correct on everything, however wrong they may be, and confirms that, by using its imagined absolute authority, then it is likely to be popular.