I have not written to you because you don't know the truth, but because you know it, and because no lie is of the truth.
And that no lie is of the truth - No form of error, however plausible it may appear, however ingeniously it may be defended and however much it may seem to be favorable to human virtue and happiness, can be founded in truth. What the apostle says here has somewhat the aspect of a truism, but it contains a real truth of vital importance, and one which should have great influence in determining our minds in regard to any proposed opinion or doctrine. Error often appears plausible. It seems to be adapted to relieve the mind of many difficulties which perplex and embarrass it on the subject of religion. It seems to be adapted to promote religion. It seems to make those who embrace it happy, and for a time they apparently enjoy religion. But John says that however plausible all this may be, however much it may seem to prove that the doctrines thus embraced are of God, it is a great and vital maxim that no error can have its foundation in truth, and, of course, that it must be worthless. The grand question is, “what is truth;” and when that is determined, we can easily settle the inquiries which come up about the various doctrines that are abroad in the world. Mere plausible appearances, or temporary good results that may grow out of a doctrine, do not prove that it is based on truth; for whatever those results may be, it is impossible that any error, however plausible, should have its origin in the truth.