In philosophy, whatever a person thinks of as “right” or “wrong” is put under the label of morality-ethics (there is no distinction between “morality” and “ethics” in modern philosophy).
Appealing to a person’s sense of “moral law” is good, because even people who deny that there is such a thing as morality/ethics, still behave as if there are propositions that they believe are right and wrong.
In philosophical moral theory, there are multiple historical models of what moral-ethical systems should look like. It would be very helpful for Christians to read over a number of different historical models, so that they would be familiar with these very different models, through the centuries. (Christians who have never done this, often assume that biblical teaching is “moral,” and everything else is nonauthoritative. This leads to a very relative and logic-free approach to moral/ethical systems. I say this, just to point out that many Christians are not ready to enter a full philosophical discussion in moral theory.)
There are other very interesting points that Christians need to be aware of. I mention just a few…
Causality, can be seen as a different presentation of truth. “What causes a statement to be true?” Causality can be examined in very physical ways (such as the applied sciences), or in very abstract ways (such as asking the question, “what is it that makes an action moral/ethical?”).
But the kinds of causality recognized in the hard sciences, are very narrow, and not at all complete. This is a basic point made in The Oxford Handbook of Causation, Beebee. And concepts of causation in the hard sciences, cannot express moral/ethical right and wrong. The hard sciences do not have the working variables, to express moral/ethical right and wrong. You cannot derive the Ten Commandments, from physics, or chemistry, or biology, or finite math. There is no way, from the hard sciences, to describe “moral law” (that is the basis of the argument presented in comments on this site, that there is a moral law giver).
A lot of Christians have embraced a very anti-intellectual approach to truth, and morality/ethics, that is really not the biblical approach. This anti-intellectual approach really does not understand “Christ, the reason/logic of God.” And avoiding the topic of what serious reasoning is, undercuts both the logical arguments in the Bible, and apologetics.
I would suggest a much, more historical, and intellectual approach.
— The hard sciences reason about a subset of reality (which excludes morality/ethics)
— The hard sciences are unable to express moral/ethical concepts
— Christians need to recognize our shared reality of valid reasoning methods
(these are the basis of both hard scientific proofs, and moral/ethical reasoning)
— Christians need to affirm that the moral/ethical “consciousness” of mankind is based on universal revelation by God, as to what is basically “right” and “wrong” (this is a much more basic argument, than “whatever is asserted in the Bible, is true.” This is Paul’s argument for the universal “conscience” of mankind. (On this point, you will find language in the New Testament referring to people who live not according to this universal morality, as people who are “living the lie.” The NT writers are appealing to a type of shared moral/ethical reality, that defines moral/ethical truth.)
— the Bible presents a type of moral/ethical “causality”: if we behave in certain ways, then God will respond to us in certain ways. The ultimate closure to this interaction, is the final judgment.
— the Bible presents “truth” as what is real, both with regard to the physical universe (here, truths agree with the results of the hard sciences, observations and experiments), and with regard to morality/ethics (here truths must agree with the universal revelation of the “conscience” and the rigors of formal logic).
If a Christian just thinks through these core ideas, they will be much further along. And they will have bridges of apologetics to the hard sciences, and formal logic, and to our shared moral/ethical reality.
I would like to see a much fuller discussion among Christians, of this shared reality that we live in.