"Because God says so" isn't an objective basis - it's a subjective basis in which the entity making the subjective appraisal has been elevated to a purportedly ultimate position.
The difference between "because God says so" and "because Jeff who lives down the street says so" isn't one of kind, but merely one of (supposed) degree. God is simply treated as a more aithoritative source than Jeff, but that doesn't somehow elevate God's assertions to objectivity.