Answer
Well, the Messiah had to be a descendent of David because Old Testament prophets indicated that. For instance, in 2 Samuel 7, it says that when your days are fulfilled and you lie down with your fathers, I will raise up your offspring after you who shall come from your body, and I will establish his kingdom. He shall build a house for my name. David had wanted to build a house for God's name, and he said, no, your descendent will do that. Well, actually that was talking initially about Solomon who would build the temple, but ultimately was talking about the Lord Jesus Christ who would build the true temple which is made of living stones, true believers. And Jesus dwells by his spirit in those true believers, so the temple symbolized the church of the Lord Jesus Christ which would be indwelt by his spirit. And it goes on to say here, your throne should be established forever. So it wasn't just talking about Solomon and the house he would build, but about Jesus Christ who would be a descendent of David's and would build the real temple in that way.
Answer by Dr. Frank Barker
Dr. Frank M. Barker, Jr., was Pastor Emeritus at Briarwood Presbyterian Church and a founder of Birmingham Theological Seminary where he served as head of the Old Testament Department. He passed away in 2021.