We are taught, for another thing, in these verses, the uselessness of religious knowledge if not accompanied by practice. We read, “If you know these things, happy are you if you do them.” It sounds as if our Lord would warn His disciples that they would never be really happy in His service if they were content with a barren head-knowledge of duty, and did not live according to their knowledge.
The lesson is one which deserves the continual remembrance of all professing Christians. Nothing is more common than to hear people saying of doctrine or duty–“We know it, we know it;” while they sit still in unbelief or disobedience. They actually seem to flatter themselves that there is something creditable and redeeming in knowledge, even when it bears no fruit in heart, character, or life. Yet the truth is precisely the other way. To know what we ought to be, believe, and do, and yet to be unaffected by our knowledge, only adds to our guilt in the sight of God. To know that Christians should be humble and loving, while we continue proud and selfish, will only sink us deeper in the pit, unless we awake and repent. Practice, in short, is the very life of religion. “To him that knows to do good, and does it not, to him it is sin.” (James 4:17.)