I find that the study of Natural Law Theory is what gives Catholic Theology the fundamental advantage over Protestant Theology. It is where Common Sense and Logic and Reason come from and the Bible should really never conflict with the teleological design of man (which is to unite with the opposite sex, have children, and then do their natural Duty of raising/protecting their own children and families.
St. Thomas Aquinas knew—since God made man rational—that we were meant to understand the things in Nature and their teleological ends-—Our intellect is meant to be used for understanding the world—since it is His creation and points to understanding of God and Truth.
I find that many people with PH.D’s are irrational and have no logic and it is because of their embracing Postmodernist philosophy which gets rid of Natural Law-—because then they can get rid of the Designer and make themselves into gods.
Your logic is much better than MANY theologians in today’s world. Pastor Bonhoeffer stated in 1931 that in America (as well as Germany) the Christianity being practiced was “religionless”—esp. by the pastors on the cover of all the prominent newspapers and magazines at the time.
Truth/Justice/Logic/Virtue/Wisdom====all go together-—can’t have any of it without Natural Law Theory. You especially have to use Logic with the Bible—not only Faith.
While I appreciate your comment that my “logic is much better than MANY theologians in today’s world,” credentials count in the academic world. Someone with better academic credentials than me needs to be responding to these Two Kingdoms people.
On the broader issue you raise of natural law, my concern about natural law is not primarily the Roman Catholic way of viewing it but rather how the Two Kingdoms people are saying we should apply natural law and not Scripture in dealing with civil government.
In fact, some Reformed people have agreed to some extent with a Thomistic view of natural law. RC Sproul and the “classical apologetics” movement are in that category. I'm not in agreement with them but that's not an issue on which I'm going to fight.
I'm not going to ask you to agree with a Reformed view of total depravity — if you are a Roman Catholic, you need to be faithful to your own doctrinal position or leave your church — but once the doctrine of total depravity is affirmed, I'm sure you can see why most Calvinists do not believe the sinful human mind is able to understand general revelation properly.
In other words, even if natural law would in theory be sufficient to understand God's will from it, our sinful brains can't make sense of it and will come up with really bad perversions of it. General revelation is enough to leave us without excuse four our sin but not enough to lead us into the right paths. Yes, “the invisible things of him from the creation of the world are clearly seen, being understood by the things that are made, even his eternal power and Godhead,” but while that's enough to leave us without excuse it's not enough to save us.
Romans 1:18-23 applies here: “For the wrath of God is revealed from heaven against all ungodliness and unrighteousness of men, who hold the truth in unrighteousness; Because that which may be known of God is manifest in them; for God hath shewed it unto them. For the invisible things of him from the creation of the world are clearly seen, being understood by the things that are made, even his eternal power and Godhead; so that they are without excuse: Because that, when they knew God, they glorified him not as God, neither were thankful; but became vain in their imaginations, and their foolish heart was darkened. Professing themselves to be wise, they became fools, And changed the glory of the uncorruptible God into an image made like to corruptible man, and to birds, and fourfooted beasts, and creeping things.”
Again, I'm not asking you to change your Roman Catholic viewpoint, only to understand the logic behind the reasons why which most (not all) Calvinists do not emphasize the use of natural law or general revelation.
Hope this helps.