What, then, is truth? It is Christ the God-man and His Gospel. And untruth is all that is not Him, all that is not in His Gospel and against the Gospel. Thus, faith in Christ is the “ministration of righteousness” (2 Cor. 3:9). He who does not serve Christ serves unrighteousness. As all unrighteousness is sin, also all sin is unrighteousness.

— St. Justin PopovichOn 1 Jn. 5:17