In fact, it is the very judgment of God which makes a person good or righteous in His sight. When we come to understand just how we were made righteous, we understand that the Christians' righteousness, and his judgment, is intimately related. It is thus not curious that God, almost from the beginning, used the signification of salt as a figure of the Covenant Promise which He has with His chosen people. Salt cannot be lacking from the sacrifice because it signifies the virtue of the sacrifice. It is the flavor which makes the meat good, or gives it it's savory or good taste.
Salt makes the meat tasty.
That sacrifice is equated to Christ, and it was the salt that made the meat good. This is equating the salt which makes the sacrifice good, to the virtue or righteousness of Christ, which makes us good. That is why God decrees that the sacrifice was to be seasoned with salt, that no sacrifice should be lacking salt. It is the savor of the sacrifice, the righteousness of Christ, which is the foundation of the Covenant. Salt is at the heart of the Covenant both in judgment, and in the virtue of Christ.