On the Hierarchical Nature of Law

Last year during my senior year of high school I became close with an atheist "secular humanist" in an attempt to bring about his conversion to at least a somewhat more reasonable state of mind. He said many things that paint the fence with regard to idiocy, but many of these things just seemed stupid to me without my mind really having a solid reason for why they seemed so off.

One particularly wrong-feeling thing he did a lot was to be outraged at the current state of national law, specifically with regard to things like gay "marriage". It always felt weird for someone who openly proclaims lack of belief in God to be outraged on moral grounds, so I thought about it a lot and figured out a good way of expressing the way I feel about this situation. I thought I'd share in case anyone else is struggling with this vague sense of stupidity in claims like these; please feel free to give me your feedback if you think I'm missing anything.
Claim (generally): "It's wrong for law to prohibit someone from attaining their sexual destiny" (Yes he said something along these lines once).

Now, mind you, this guy was and is not Christian in any way, so I can't really make any of the obvious arguments against this degeneracy, but even outside of the sphere of Christian thought, something feels fundamentally off about this statement. Here's why.

In a nation, there are different levels of law. Lets take a theoretical nation where there exist 3 levels of civic law: municipal, state, federal. If there is a state law in one state in this country, then no municipality which resides in the jurisdiction of the state may override that law. Such is the nature of law. Similarly, no state my override a federal law. If on some occasion, it comes to pass that a municipal law is out of touch with the law of the state which resides over it, then the individuals of the municipality are righteous in demanding that such law be changed in order to exist in harmony with their state. Moreover, individuals in a state might find themselves in a situation where their state is out of sync with laws existing at the federal level. These individuals, too, would be righteous in their outrage focused on the disobedient state, until such a time as the state rights its law in accordance with federal law.

However, the reverse of these situations is NOT righteous. If it is law in a certain, fun-loving municipality that all men be required to wear bowties every Friday, then that is the law in that municipality so long as it does not intrude upon the laws of the state and nation to which it belongs. That said, it DOES NOT FOLLOW that citizens would be logical in their outrage if the state to which their municipality belongs does not observe this "bowtie Friday" and they demand that it begin to. Likewise, no state would be righteous in their outrage if federal law does not change to meet their own laws. This is common sense, as it is the fundamental nature of law.
It therefore follows that any individual who wishes to declare outrage over any law at any level of law be required to provide substance to his outrage in the form of a higher level of law to the one being focused on. In other words, only a higher level of law can be used to show that a law is unjust. For example, if an individual thinks it is unjust that a state restrict access to firearms, he must show that a higher level of law (probably federal law) guarantees the right to said firearms.

If an individual can not provide substance to back up his outrage over a law, then his outrage is illogical. He is simply projecting his own internal law onto a law which exists above him. When we consider the conundrum of federal law and its possible unjustness, as Christians, we have a simple solution. There exists, we posit, and EVEN HIGHER level of law than that of the federal government: the law of God. Since the law of God is a law that all are subject to, the law of God is superior to any federal law. So, similar to how a state should change its law in accordance with federal law, so too must federal law change in accordance with God's law.
This means that whichever law is highest in existence is necessarily just, since a law being unjust requires that a higher law contradict it.

This is why all of those Steven Fry-esque posts about how "God is unjust" are absurd. In saying such things they are either implying that there is some law above God's own law (a logical contradiction stemming from the definition of God and his law), or they are projecting their own feelings on certain matters as objective reality, in place of LITERAL objective reality.

This is also why my friend's statement is so indubitably wrong. In taking issue with federal law on moral grounds, he is inferring that there exists a higher law than federal, yet by his own admission, there exists none! Morals are subjective! In other words, they don't objectively exist. What he is doing is either self contradictory in that he claims no higher law than federal yet infers it, or pathetic and illogical, by substituting his own subjective code of feelings in where federal law objectively exists as the definition of justice.