C.S. Lewis on the common moral law

C.S. Lewis firmly believed in what he called the Tao, the common moral law understood by almost all human beings. Lewis’ concept of the Tao is quite similar to how many Mormons understand the Light of Christ.

Lewis responded to those who believed there were substantial differences in moral understanding across cultures with this:

I have met people who exaggerate the differences, because they have not distinguished between differences of morality and differences of belief about facts. For example, one man said to me, “Three hundred years ago people in England were putting witches to death. Was that what you call the Rule of Human Nature or Right Conduct?” But surely the reason we do not execute witches is that we do not believe there are such things. If we did — if we really thought that there were people going about who had sold themselves to the devil and received supernatural powers from him in return and were using these powers to kill their neighbours or drive them mad or bring bad weather, surely we would all agree that if anyone deserved the death penalty, then these filthy quislings did. There is no difference of moral principle here: the difference is simply about matter of fact. It may be a great advance in knowledge not to believe in witches: there is no moral advance in not executing them when you do not think they are there. You would not call a man humane for ceasing to set mousetraps if he did so because he believed there were no mice in the house.

So far, so good. But is the Light of Christ really the same as this common moral law?

Don’t misunderstand my question. I believe that a common moral law does exist, both for theological reasons (a belief in a transcendent order of things rooted in the reality of God) and scientific reasons (evolutionary psychology.) In other words, I am a disciple both of Moses and of James Q. Wilson.

But I’m not convinced this is what is meant by the Light of Christ as explained the Book of Mormon. Doesn’t the name suggest that it is patently tied to Christ? My reading is that the Light of Christ is the ability to judge good or evil by whether it leads us to Christ — a rule that presupposes a belief in Christ.

Thoughts?