Doctrine of Life #60
60. That the stone tablets on which the law was written were called the Tablets of the Covenant, and that because of them the Ark was called the Ark of the Covenant, the law itself being the covenant, see Numbers 10:33; Deuteronomy 4:13, 23, 5:2-3, 9:9; Joshua 3:11; 1 Kings 8:19, 21; Revelation 11:19. And many other places.
The law was called a covenant because a covenant symbolizes conjunction. We are accordingly told regarding the Lord that He would be “as a covenant to the people” (Isaiah 42:6, 49:8). He is called, too, “the Messenger of the covenant” (Malachi 3:1), and His blood “the blood of the covenant” (Matthew 26:28, Zechariah 9:11, Exodus 24:4-10). That is why the Word is called the Old Covenant and New Covenant.
Covenants are also made as testaments of love, friendship, and fellowship, thus for the sake of conjunction.
Exodus 25:17-21
17
You shall make a mercy seat of pure gold. Two and a half cubits shall be its length, and a cubit and a half its breadth.
18
You shall make two cherubim of hammered gold. You shall make them at the two ends of the mercy seat.
19
Make one cherub at the one end, and one cherub at the other end. You shall make the cherubim on its two ends of one piece with the mercy seat.
20
The cherubim shall spread out their wings upward, covering the mercy seat with their wings, with their faces toward one another. The faces of the cherubim shall be toward the mercy seat.
21
You shall put the mercy seat on top of the ark, and in the ark you shall put the testimony that I will give you.
