The Holy Spirit is part of the Godhead, also known as the trinity: the Father, Son and the Holy Spirit. Within the trinity, each person has a distinct role that is unique but also intimately united with the other parts of the trinity.
The Father creates, the Son rescues and the Spirit re-creates, making it so we are actually made new in and through Christ.
The fullness of the Spirit of Christ is difficult to explain and understand, as are many of the incredible attributes of Christ. There are, however, some attributes of the Holy Spirit that we do know and can explain.
First, the Spirit of Christ is divine and Holy. He is an active person and the executive of the Godhead. There are many misconceptions about the Spirit. Some associate the Spirit with mystical states and artistic inspirations, both Christian and pagan. Others link the Spirit only with unusual Christian experiences feeling “high”, seeking visions, receiving revelations, speaking in tongues, healing. But these are secondary elements of the Spirit’s work, if they come from the Spirit at all.
The Old Testament mentions the Spirit in connection with creation, both divine (Genesis 1:2) and human (Exodus 31:1-6); the inspiring of God’s spokesmen (Isaiah 61:1; the Nicene Creed states that the Spirit “spoke by the prophets”); the equipping and enabling of God’s servants (judges, kings, etc.; e.g., Judges 13:25; 14:19; Isaiah 11:2; Zechariah 4:6); and the bringing about of godliness in individuals and in the community (Psalm 51:11; Ezekiel 36:26; 37:1-14; Zechariah 12:10). All this gains deeper meaning in the New Testament, where the Spirit is shown to be a personal agent distinct from the Father and the Son, and is spoken of as the Spirit of Christ (Romans 8:9, 1 Peter 1:11).
The key to understanding the New Testament view of the Spirit’s work is to see that his purpose is identical with the Father’s that is, to see glory and praise come to the Son.
First, the Spirit served the Son throughout his earthly life from the moment when he was “conceived by the Holy Spirit” (Matthew 1:20). The spirit’s dove-like descent on him at his baptism showed not only that he was the Spirit-giver, but also that he himself was Spirit-filled (Luke 4:1). It was “through the eternal Spirit” that he offered himself in sacrifice for us (Hebrews 9:14).
Second, the Spirit now acts as Jesus’ agent “another Comforter” (helper, supporter, advocate, encourager). He shows Jesus to us through the gospel, unites us to him by faith, and indwells us to change us “into his likeness” by causing “the fruit of the Spirit” to grow in us (2 Corinthians 3:18).
Third, the Spirit gives to every Christian one or more gifts (i.e. capacities to express Christ in serving God and man). The only sure signs are that the Christ of the Bible is acknowledged, trusted, loved for his grace and served for his glory, and that believers actually turn from sin to the life of holiness which is Christ’s image in his people.