The law of God is the righteousness of God. It may not be amiss to review the proof on this point. David, in these words, bears witness to the fact that the commandments are themselves righteousness: "My tongue shall speak of Thy word; for all Thy commandments are righteousness." Ps. 119:172. Since there is no righteousness but that of God, the commandments must be His righteousness; but we have still more direct evidence. The prophet Isaiah thus contrasts the things of earth with the righteousness of God: "Lift up your eyes to the heavens, and look upon the earth beneath; for the heavens shall vanish away like smoke, and the earth shall wax old like a garment, and they that dwell therein shall die in like manner; but My salvation shall be for ever; and My righteousness shall not be abolished." Isa. 51:6. In the next verse he proceeds to tell what this righteousness is: "Hearken unto Me, ye that know righteousness, the people in whose heart is My law." Because the law is the righteousness of God, it enables those who are instructed in it to "give judgment upon good or evil."
The text says, "My righteousness shall not be abolished." Since there can be no question but that "righteousness" is here used with reference to the law of God, we may properly substitute "law" for "righteousness," thus: "The earth shall wax old like a garment, and they that dwell therein shall die in like manner; but My salvation shall be for ever, and My law shall not be abolished." This gives the exact meaning, and is no more positive than we shall find stated elsewhere.
God is from everlasting to everlasting. Ps. 90:2. As He cannot exist separate from His nature, or, in other words, separate from Himself, and the law is the transcript of His nature, it necessarily follows that the law exists from everlasting to everlasting. And since created beings, who are all subjects of God's government, cannot obey an abstract principle, but must have that principle clearly defined, we know that at least from the time that God created intelligent beings as subjects of His government, the law must have existed in written form, or must have been expressed in definite language. And from the beginning of His creation to everlasting ages, it must continue so to exist.
This is exactly what we are taught by the words of Christ in the sermon on the mount. Said he: "Think not that I am come to destroy the law, or the prophets; I am not come to destroy, but to fulfill [to ratify, establish, or teach]. For verily I say unto you, Till heaven and earth pass, one jot or one tittle shall in no wise pass from the law, till all be fulfilled." Matt. 5:17, 18. Here two things are mentioned, the law and the prophets. Christ did not come to destroy either one. He came in fulfillment of prophecy, and also to teach the law, which he did in the sermon on the mount. He did not, however, fulfill all the prophecy; for some of it reaches far beyond His first advent. For instance in Ps. 89:20-29 we read the following prophecy concerning the kingdom of David, over which Christ, as the Son of David, is to rule:--
"I have found David My servant; with My holy oil have I anointed him; with whom My hand shall be established; Mine arm also shall strengthen him. The enemy shall not exact upon him; nor the son of wickedness afflict him. And I will beat down his foes before his face, and plague them that hate him. But My faithfulness and My mercy shall be with him; and in My name shall his horn be exalted. I will set his hand also in the sea, and his right hand in the rivers. He shall cry unto Me, Thou art my Father, my God, and the Rock of my salvation. Also I will make him My firstborn, higher than the kings of the earth. My mercy will I keep for him for evermore, and My covenant shall stand fast with him. His seed also will I make to endure for ever, and his throne as the days of heaven."
In verses 35-37 we read further:--
Once have I sworn by My holiness that I will not lie unto David. His seed shall endure for ever, and his throne as the sun before me. It shall be established for ever as the moon, and as a faithful witness in heaven.
Here is a prophecy that will be in process of fulfillment as long as the sun and moon endure, even to all the days of heaven. Now the words of Christ are that "one jot or one tittle shall in no wise pass from the law till all be fulfilled." Till all what be fulfilled? Evidently till all the prophets be fulfilled, for He is speaking of the prophets, in connection with the law. Then, in view of the prophecy that we just read, we know that not the slightest change can be made in the law so long as Christ reigns on the throne of David; and that will be throughout eternity.