Biblical Inerrancy - mandatory to be Christian?

[Whateverist]

1. Moral relativism is the state in which there is no absolute moral authority. (MR -> No MA)
2. If there is no absolute moral authority, there is no way to resolve competing moral claims (No MA -> No mc)
3. If there is no way to resolve moral claims, all morals are equally truth from an objective standpoint (No MC -> ET)
4. If all morals are equally true from an objective standpoint, all morals are equally false (ET -> EF)
5. If all morals are equally false, a state of nihilism is reached where people have no obligation to obey any morals. (EF = nihilism)

It looks superficially impressive when you line it up like this but the fact of the matter is society manages to reach certain agreements as to what transgressions will and won't be accepted. We codify this into law. Its being enforced as the law depends not at all on its correspondence to any objective morals. We can still make sense of all the feelings we have when we are badly treated by others without thinking - huh, that was objectively bad to do. Give it up. Morals do not depend on any platonic ideals.