21 This is the key of the treasury of the house of God, which is typified by the house of David for the building up of the kingdom of God—39:2; 2 Sam. 7:16.
6b As the real David, the greater David, Christ has built up the house of God, the real temple, and He has set up the kingdom of God, the dominion in which He exercises full authority to represent God; therefore, He holds the key of David—Matt. 1:1; 12:3-8; 16:18-19.
7c The fact that Christ has the key of David signifies that He is the center of God’s economy; He is the One who expresses God and represents Him, the One who holds the key to open everything in God’s dominion—Col. 1:15-18.