The Way the Righteous King Works
The Spirit of God is the agent of change just as much for Israel in Isaiah’s day as it is for us. There is no hope for humanity or transformation in an individual without the Holy Spirit. The Holy Spirit is the means by which the Righteous King executes his reign, therefore God the Creator, God the Son, and God the Holy Spirit are all one sovereign and divine being.
Isaiah proclaims that as a result of the Spirit of God being poured out; wildernesses will become fruitful fields (v.15), which means that those of us whose lives have become purposeless wildernesses will again bear purposeful fruit when the Holy Spirit has dominion in our hearts. This is also what the apostle Paul meant in his letter to the Galatians, “Live by the Spirit, I say, and do not gratify the desires of the flesh. For what the flesh desires is opposed to the Spirit, and what the Spirit desires is opposed to the flesh; for these are opposed to each other, to prevent you from doing what you want.” (Galatians 5:16-17 NRSV)
Since Isaiah’s day the Holy Spirit has indeed been poured out, first the Holy Spirit came upon Jesus when he was baptized and God the Creator gave his approval (Matthew 3:13-17), then Jesus breathed the Holy Spirit on his disciples when he appeared to them after his resurrection (John 20:22), and again the Holy Spirit was poured out on the day of Pentecost causing all to provision the works of God's in their native language (Acts 2:4). Even the apostle Peter proclaimed that all we need to do is repent, and be baptized in the name of Jesus Christ for the forgiveness of our sins, and we will receive the gift of the Holy Spirit (Acts 2:38).
What a privilege we share today that Isaiah could only hope for in his time, that the Spirit that we all need to live lives acceptable to God is already at work. It was first manifested in the life and witness of Christ our Lord, the Righteous King whom Isaiah prophesied about, and that same Spirit has been readily available to us and gives us peace, confidence, and trust in God forever (v.17).