Israel knew the mechanics of the Lord’s worship, the sacrifices, the feast days, and other ceremonies connected with that worship; but they did not know God. In fact, the very religious worship and service of God had become to them, as they may be to us, a deceptive displacement of God Himself. The worship and service of God are vain unless we know the God whom we worship and serve (see Matt. 7:22, 23; John 17:3).