Of the increase of his government and peace
there will be no end.
He will reign on David’s throne
and over his kingdom,
establishing and upholding it
with justice and righteousness
from that time on and forever.
The zeal of the LORD Almighty
will accomplish this.
Isaiah 9 is a prophecy about Jesus that has yet to be fulfilled. The disciples and others who followed Jesus expected to see it fulfilled in their lifetime with the overthrow of the Roman government.
During the Millennial Kingdom, Jesus will reign from David’s throne for a thousand years and will establish justice and righteousness in the world. It will be a period of time unlike any other in humanity as Jesus is the King of Kings and Lord of Lords.
We still see some of the benefits of Jesus’ kingdom here in the church age, if not a literal reign that is still to come. Today Jesus reigns in the hearts and minds of Christians.
Jesus spoke extensively to His disciples about why He must leave and that He would not leave them alone but would instead send the Holy Spirit. One of the duties of the Holy Spirit is to convict the world of sin and guilt in regard to righteousness.
So spiritually we see Jesus’ kingdom in progress with the Holy Spirit working to establish righteousness in the hearts of men. In the future Jesus will literally reign from David’s throne and will personally establish a kingdom of unending righteousness.