The Hebrew ruach and Greek pneuma mean ‘breath’ or ‘wind’ and are translated by ‘spirit’, denoting an unseen life-giving force. United with ‘holy’, the force is said to be divine, though the combination of the two words occurs only three times in the OT: (Isa. 63: 10, 11; Ps. 51: 11).
The spirit in Gen. 1: 2 is the power of God by which he creates the universe. It is the spirit which enlivens the community with hope for the future (Ezek. 11: 14–21) and which breathes life into the dry bones in the vision of the valley (Ezek. 37: 1–10). It is prophesied that the future messianic era will be marked by the gift of God's spirit on all people regardless of age or gender (Joel 2: 28).
There is little in the synoptic gospels about the Holy Spirit, except at the birth of Jesus (Matt. 1: 18; Luke 1: 35) and his baptism (Mark 1: 8), and it is said that the Spirit operates in the ministry of Jesus against the forces of evil (Matt. 12: 28). The paucity of references may be due to the belief that the work of the Holy Spirit was only apparent after Jesus' resurrection (John 7: 39).
After the resurrection the Spirit is said to be the agent of the missionary zeal of the Church (Acts 1: 8) as Jesus had promised (Luke 24: 49); fifty days after Easter (Acts 2: 1) or on Easter evening (John 20: 22) the Spirit was given, the Spirit of Christ (Rom. 8: 4; 2 Cor. 3: 18). Paul does not identify Christ and the Spirit, even in 2 Cor. 3: 17, but there is an identity of function in the work of redemption. The Spirit works through the Church, and the Acts of the Apostles is largely the story of the guidance by the Spirit of apostles and evangelists. In the gospel of John the Spirit is five times called the ‘Paraclete’, meaning a defending counsel. He is to promote the disciples' understanding of the truth concerning Christ.
Just as the Spirit fills the Church (Eph. 4: 4), it is also the power which guides individual believers and endows them with a diversity of gifts for the service of the whole Body (1 Cor. 12: 7), not to be confused with evil spirits (Rom. 8: 15) which foment dissension (1 Tim. 4: 1). ‘Spirit’ is therefore contrasted with ‘flesh’, characteristics respectively of the life of the new age and the former age.
In later Christian theology, the Holy Spirit is the third person of the Trinity—not a doctrine explicitly discernible in the NT, but it is maintained that the NT writers were feeling their way to what the Fathers in due course, operating in a Greek philosophical climate, were to define. They used the terminology of their times to draw out the metaphysical implications of the NT data.