The Bible refers to the Spirit of God in hundreds of passages. He is named many ways, like: Holy Ghost, Holy Spirit, God’s Spirit, or the Spirit of God. In other places, He is referred to as the Finger of God, the Spirit of Truth, the Comforter, or the Seven-fold Spirit.
Who is the Holy Spirit? Is He a Person? Or should we interpret Him as God's Power? Or God Himself?
The Bible, from start to finish, talks about this Spirit. The very first chapter of the Bible, Genesis 1, shows us that the Spirit of God was involved with the creation of the world. In the last chapter of the Bible, Revelation 22, the Bride and the Holy Spirit call out together for the return of Jesus on earth. Still, there is a lot of confusion about this subject. That is not necessary.
In the timeframe of the Old Testament, the Lord is forming a nation, completely for Himself. He is forming this nation, so that He can be their God. He pulls that nation away from idolatry. It is important that this new nation, later called Israel, knows from the very beginning that there is only one God.
Deuteronomy 6:4 (NIV)
That is why the Person of the Holy Spirit is not specifically described in the Old Testament. If we keep reading, however, we can see that the Bible often speaks of the Spirit of the Lord, as someone who can judge, someone who can be disappointed, and who can handle the Word of God. It is beautiful to see that the prophet Isaiah was already talking about the Holy Spirit being poured out on Jesus, so that He can do His work (like proclaiming the Good News and healing the sick). And this was 700 years before He was even born!
The public life of Jesus started with His baptism, and afterwards the bestowment of the Holy Spirit.
Matthew 3:16 (NIV)
Starting from that moment, Jesus began the work He came to do on earth. Immediately after this spectacular moment, He was confronted by the devil. We can read about this ‘temptation’ in Matthew 4 and Luke 4. Throughout His entire life, Jesus lives in great dependence of His Father (John 5:19). Jesus heals and frees people who were sick and bound. In order to show us that this dependence on His Father is a result of the Holy Spirit resting on His life, He refers to a passage written by Isaiah (Luke 4:18-21).
The Holy Spirit is not only visible through Jesus’ deeds, but also through His teachings. He talks elaborately about the Holy Spirit, who was to be sent by the Heavenly Father to His disciples. Jesus taught that this would happen after Jesus had died, risen and ascended to heaven.
15 “If you love me, keep my commands. 16 And I will ask the Father, and he will give you another advocate to help you and be with you forever— 17 the Spirit of truth. The world cannot accept him, because it neither sees him nor knows him. But you know him, for he lives with you and will be in you. 18 I will not leave you as orphans; I will come to you.
John 14:15-18 (NIV)
Here, we can read that the Holy Spirit is called an ‘advocate’ (also called the Comforter, in other translations). He is also the Spirit of the truth. Jesus does not leave His disciples as orphans, but He will return to them (and to all of us), through the Holy Spirit of the truth, who will live in us and shall forever be with us!