Miracles 5.10 "... we must believe that the conscience of man is not a product of Nature."

"Human beings, all over the earth, have this curious idea that they ought to behave in a certain way, and can not really get rid of it." Mere Christianity, Book 1, Chapter 1, paragraph 11

…how do we decide what is good or evil? The usual answer is that we decide by conscience. But probably no one thinks now of conscience as a separate faculty, like one of the senses. Indeed, it cannot be so thought of. For an autonomous faculty like a sense cannot be argued with; you cannot argue a man into seeing green if he sees blue. But the conscience can be altered by argument; and if you did not think so, you would not have asked me to come and argue with you about the morality of obeying the civil law when it tells us to serve in the wars. Conscience, then, means the whole man engaged in a particular subject matter.

But even in this sense conscience still has two meanings. It can mean (a) the pressure a man feels upon his will to do what he thinks is right; (b) his judgment as to what the content of right and wrong are. In sense (a) conscience is always to be followed. It is the sovereign of the universe, which "if it had power as it has right, would absolutely rule the world." It is not to be argued with, but obeyed, and even to question it is to incur guilt. But in sense (b) it is a very different matter. People may be mistaken about wrong and right; most people in some degree are mistaken. By what means are mistakes in this field to be corrected? Why I Am Not a Pacifist, paragraph 1 & 2

All men at times obey their vices: but it is when cruelty, envy, and lust of power appear as the commands of a great super-personal force that they can be exercised with self-approval. The first symptom is in language. When to 'kill' becomes to 'liquidate' the process has begun. The pseudo-scientific word disinfects the thing of blood and tears, or pity and shame, and mercy itself can be regarded as a sort of untidiness. A Reply to Professor Haldane, Of Other Worlds, last paragraph