What is conscience? One writer has compared conscience to a sundial, which is able to give fairly good time by day when the sun is shining on it but is totally unable to give any kind of time by night. We imagine a boy and a girl outside on a date, and the girl asks, “What time is it? Mother told me to be home by eleven o’clock.” It is pitch black when she says this. The boy says, “Well, here’s a sundial. Let’s see.” He strikes a match and holds it up to the gnomon. “Look, it’s only eight-thirty!” If he moves the match around he can make the sundial say any time he wants. Seven-thirty! Five-thirty! Twelve noon! That is no good, you see. Mother said that her daughter was to be home by eleven o’clock sun time.
Another way of showing why it is inadequate to “let your conscience be your guide,” as we say, is that we can wrestle our conscience down. The first time you are tempted to do something you know you should not do, your conscience will thunder, “No!” So, of course, you do not do it.
But you begin to work on your conscience. You talk to it, saying, “Well, I realize that for the reason I had in mind at first it probably was not right for me to do what I wanted to; you were no doubt right to tell me not to. But I’ve been thinking it over, and I think that although I couldn’t do it for the reason I mentioned last week, I could probably do it for this reason . . .”
Again your conscience says “No!” but not quite as loudly as before.
A week later you try again. “Yes, I understand that neither of those first two reasons was very good. But I think maybe I could do it for this reason.
Your conscience says “No” (quietly). You add, “And here is another reason I’ve thought of…” Your conscience says nothing. So you go out and do it. There is only one way in which conscience can be a sure guide to right conduct, and that is when the light of God’s Word is shining on it. When the light of God shines on the sundial of your conscience you get the right time. But apart from that the conscience is like a trained circus dog. You whistle once, and it will stand up. You whistle twice, and it will roll over. The third time it will play dead.