This is the second in my basic fundamentals of Christianity. Whereas the previous post was benign, this one should exasperate you if you really understand what I'm saying. Morality and moral laws, as humans use it, is nothing more than manipulation. First, however, let me criticize moral laws in general.
Moral logic, in general, follows this pattern:
A is true, and B is true, so action C is a moral behavior.
A traditional Christian moralist would like say it like this:
God gave us his law, God is the ultimate judge, so actions prescribed in that law are moral behaviors.
If this were an immutable truth there would be little room sin. Traditional Christianity paints any rejection of this as mere rebellion, but there are other more fundamental problems.
What if someone doubts that God exists? What if the Bible isn't perfectly clear on defining action C? The moral compulsion breaks down. Sprinkle a little skepticism on A, B, and C, and the moral law fails.
More universally, any set of A, B, and C is subject to doubt. If someone doesn't want to do action C, know that they will dedicate their energies to casting doubt on A and B.
A more experienced logician will claim that A and B are axioms. That they are self-evident truths. Skepticism, however, is not bound by anything. The skeptic will find a way. They always do.
Doesn't this imply an ethical nihilism that nothing is moral or immoral? Yes it does, and I'm not afraid, and you shouldn't be either.