Forever is a long time.
Forever is so long, in fact, that when one uses the term in normal conversation, it is probably meant to be taken as hyperbole rather than literally.
“This car ride is taking forever.” “We’ll be friends forever.”
But God used the term literally in a covenant He made with David. Forever is how long God told David that David’s house would stand.
God was not exaggerating when He said “forever”. David’s response clearly shows that he received the promise in faith and took it literally.
Further evidence of the eternal throne of David is found in a Psalm.
God promising David an eternal house is astounding. How would God fulfill His promise? There are two possible ways.
The first way is that God would bless the fruit of the womb so that a son of David will always beget a son of David, and every time a son of David dies, God will raise up a different son of David to replace him. However, this solution does not comport with the other teachings of Scripture, for this earthly life does not go on forever. There will be a final judgment of God where men are sent to everlasting life or everlasting contempt. Once the judgment occurs, there will be no more death for the living, and therefore there will be no need to replace a son of David due to death. Therefore this cannot be the ultimate fulfillment of the covenant. Another way is needed.
The other way, the second possibility, is that there will be a son of David who will not relinquish the throne due to death (and who would technically negate the need for further sons to be born in David’s line). This son of David could either be born and never die, or could die but be resurrected from the dead by God, never to die again.
Now what is the point of saying all these things? Quite simply, there are only two groups of people who legitimately believe in the Davidic covenant: Jews and Christians. Jews are waiting for the son of David to be born and to take David’s throne forever. As Christians, we believe that Jesus of Nazareth is the Son of David that has assumed the throne forever.
Here is the lineage of Jesus of Nazareth showing that He is a son of David:
Here is evidence that Jesus is the King of the Jews ruling from on high.
And when they had crucified Him, they divided up His garments among themselves by casting lots. And sitting down, they began to keep watch over Him there. And above His head they put up the charge against Him which read, “This is Jesus the king of the Jews.” Matthew 27: 35 – 37
“Men of Israel, listen to these words: Jesus the Nazarene, a man attested to you by God with miracles and wonders and signs which God performed through Him in your midst, just as you yourselves know – this Man, delivered over by the predetermined plan and foreknowledge of God, you nailed to a cross by the hands of godless men and put Him to death. But God raised Him up again, putting an end to the agony of death, since it was impossible for Him to be held in its power. For David says of Him, ‘I saw the LORD always in my presence; for He is at my right hand, so that I will not be shaken. Therefore my heart was glad and my tongue exulted; moreover my flesh also will live in hope; because You will not abandon my soul to Hades, nor allow Your Holy One to undergo decay. You have made known to me the ways of life; You will make me full of gladness with Your presence.’ Brethren, I may confidently say to you regarding the patriarch David that he both died and was buried, and his tomb is with us to this day. And so, because he was a prophet and knew that God had sworn to him with an oath to seat one of his descendants on his throne, he looked ahead and spoke of the resurrection of the Christ, that He was neither abandoned to Hades, nor did His flesh suffer decay. This Jesus God raised up again, to which we are all witnesses. Therefore having been exalted to the right hand of God, and having received from the Father the promise of the Holy Spirit, He has poured forth this which you both see and hear. For it was not David who ascended into heaven, but he himself says: ‘The LORD said to my Lord, “Sit at My right hand, until I make Your enemies a footstool for Your feet.”’ Therefore let all the house of Israel know for certain that God has made Him both Lord and Christ – this Jesus whom you crucified.” Acts 2: 22 – 36
…Jesus, the author and perfect of faith, who for the joy set before Him endured the cross, despising the shame, and has sat down at the right hand of the throne of God. Hebrews 12: 2
God fulfilled the Davidic covenant in a most spectacular way. Jesus fulfilled the bloodline requirement since He is a son of David. And Jesus fulfilled the eternal requirement because He, as God, took on human flesh forever and will live forever, reigning as king.