The most potent lies may be those cloaked in and wrapped around a powerful truth. The closer to Truth a lie may be, the greater its power to deceive.
And almost a proof of God it is, for it highlights that we all appeal to the same moral law -- a law of God's making, not our own. There is only one moral law. We cite it in all discussions. We may try to dismiss it in our minds, but we have to assert our innocence by it in all disputes. Lewis began his wonderful book "Mere Christianity" with just that insight.