"The Spirit of the Lord GOD is upon me, because the LORD has anointed me to bring good news to the poor; he has sent me to bind up the brokenhearted, to proclaim liberty to the captives, and the opening of the prison to those who are bound."
How is it that God's promised light goes out to the nations? By preaching. In Acts 2, we see the Spirit of the Lord falling on the first church and instantly they start preaching the Gospel. The Holy Spirit is given for comfort, for building up, for instruction, and for proclaiming Jesus! If we are alive in Christ we must proclaim Him in His own Power, the Holy Spirit.
Here is our job description as preachers: give good news, bind up, proclaim Liberty, open prisons, tell of Gods favor and His vengeance, and turn mourners into dancers that God might be glorified. Who is adequate for these things? No one, no one but God Himself. So the Lord sends Himself to accomplish His mission through us. This is the work of the Holy Spirit: to turn meek and frightened believers into bold and gentle heralds of the Kingdom.
"I will greatly rejoice in the LORD; my soul shall exult in my God, for he has clothed me with the garments of salvation; he has covered me with the robe of righteousness..." (v. 10)