When we’re thinking about morality we sometimes get a little too focused upon the individual man. JPII points out that Christian morality isn’t something from which the society may demur:
In the Book of Genesis we read: “The Lord God commanded the man, saying, ‘You may eat freely of every tree of the garden; but of the tree of the knowledge of good and evil you shall not eat, for in the day that you eat of it you shall die’” (Gen 2:16-17).
With this imagery, Revelation teaches that the power to decide what is good and what is evil does not belong to man, but to God alone. The man is certainly free, inasmuch as he can understand and accept God’s commands. And he possesses an extremely far-reaching freedom, since he can eat “of every tree of the garden”. But his freedom is not unlimited: it must halt before the “tree of the knowledge of good and evil”, for it is called to accept the moral law given by God. In fact, human freedom finds its authentic and complete fulfilment precisely in the acceptance of that law. God, who alone is good, knows perfectly what is good for man, and by virtue of his very love proposes this good to man in the commandments.
God’s law does not reduce, much less do away with human freedom; rather, it protects and promotes that freedom. In contrast, however, some present-day cultural tendencies have given rise to several currents of thought in ethics which centre upon an alleged conflict between freedom and law. These doctrines would grant to individuals or social groups the right to determine what is good or evil. Human freedom would thus be able to “create values” and would enjoy a primacy over truth, to the point that truth itself would be considered a creation of freedom. Freedom would thus lay claim to a moral autonomy which would actually amount to an absolute sovereignty. [VS §35, italics in original]
It is not for man—whether by himself, or in society—to declare what is good or evil. That authority rests with God alone. So states have no authority to compel or to authorize behavior that God says is evil, just as a man has no right before God to call his own sins good.