Do you truly believe that man can force others to obey whatever law the majority deems fit? That morality is relative and that the majority decides on the final standard?
By what standard can the most people pass judgment on the statements & actions of others? Who sets that Standard and how can we know it is correct? There are majorities that believe killing Christians is Moral and just, how can you argue otherwise. You have no moral authority over them.
Oh geez. You seem to be saying that the only alternatives are anarcy or Communism. Any government control at all == total Communism. Yeah, I was almost an anarcho-libertarian once myself.
Strictly speaking, morality is relative to human nature, since its purpose is to provide a consistent framework for action that allows for humanity to flourish (to "maximize our eudaimonia", as Aristotle might say). But since human nature doesn't change, morality is essentially absolute. The problem is, the optimum moral framework for enhancing eudaimonia is not self-evident. Thus the need for competition between societies & civilizations, and for federalism, for that matter, and the need to learn from history.
There are some Truths that have become self-evident facts over time, in the sense that today it would be perverse to withhold assent: The right of free speech, the right of an individual to self-defense, the right of a massive group to self-defense against the government itself (i.e. secession), the right to contract, the prohibition against slavery (including slavery to enforce a contract), a representative form of government, etc. These things are locked in place in a Constitution, and only an overwhelming supermajority can change them.
In fact, the need for a gov't-power-limiting constitution itself is self-evident to any student of history.
On the other end, questions like "what goods & services should be produced?" can only be answered by the marketplace - which is a framework where both majorities and dedicated minorities can find satisfaction.
In between these two, you have the laws that get passed by Congress & by the individual states. When it's running well, the best & most universal ideas take over the meme pool in a process of Lamarckian evolution. You end up with a lot of laws that are imposed on us that are (indirectly) supported by the majority, but at least they had to endure some competition in the marketplace of ideas to achieve their dominance.
It's very messy. But until you can prove to me that this supernatural Authority Figure person actually exists, as opposed to being someone you merely hope exists for the sake of society, then it's the best framework we can hope for.