I think Martin provides the answer in my column. It's a name for the thing that tempts you to do terrible things against your conscience. According to this view, God created people, but he created them with free will, and the Devil tempts people to act against God. In our conversation, Martin talked about the three personas the devil takes on in people's lives, according to St. Ignatius.
1. the spoiled child: I want this and I want it now.
2. the false lover: the liar, the secret keeper, the unfaithful.
3. the army commander: the tyrant, the one who goes for the weak spot in others.
these are helpful ways, I think, to think about the way humans are tempted away from what their moral consciences tell them.