The change from “Holy Ghost” to “Holy Spirit” in the English translations of sacred texts was literally correct and long overdue. (Other languages always translated the original Hebrew and Greek words with “spirit.”)
Middle Eastern culture sheds significant light on the evolution of the meaning of these Hebrew and Latin words.
Wind And Power
The Hebrew word ruah, the Greek pneuma, and the Latin spiritus all basically mean “air in motion,” “breath ” or “wind.” The root meaning is power.
Apart from human and animal power, wind was the main observable energy source in the ancient world. Sometimes it was experienced as a cool, refreshing breeze (Gen 3:8), other times as a strong wind (Ex 10:13, 19), and sometimes it had hurricane or tornado force (1 Kgs 19:11).
Poetic texts in ancient literature frequently preserve archaic expressions. Thus, Ps 18:15 (also 2 Sam 22:16) describes the wind as God’s breath.
Then the channels of the sea were seen, and the foundations of the world were laid bare at your rebuke, O Lord, at the blast of the breath of your nostrils. (see also Ex 15:8; 2 Sam 22:16; Hos 13:15; Is 30:28; Job 4:9).
Thus, the primitive understanding of wind in the Bible is as the breath of a very powerful being.
Wind As Liquid
Also interesting is the ancient understanding of wind (and water and fire) as possessing what we now consider to be the properties of liquids. This explains why the ancients believed that the wind or spirit could be “poured out”:
Wind, God's Breath
Since human beings tend to perceive and understand God from a human perspective, our ancestors in the faith spoke anthropomorphically of God’s arm (Is 40:15), hand (Dt 2:15). face (Gn 33:10), mouth (Ps 33:6), and breath (Jb 32:9; 33:4), which they understood to be God’s vital power or spirit.
The Old Testament never presents the spirit of God as a person but rather as the power by which God acts in human life. This power is no more distinct or separate from God than a hand or mouth.
Even so, God’s power or breath acts outside of God and can be “sent” (Is 48:16), “placed” (Is 63:11), or “poured.”
The Holy Wind, Breath, Spirit
This background helps a modern believer to appreciate what the apostles and Jesus understood to be taking place in today’s gospel.
Jesus announces that he is sending the apostles just as the Father sent him. Then he “breathes” on the Eleven (Jn 20:22), imitating the moment of creation when God “blew” up the nostrils of Adam and brought him to life (Gn 2:7).
The risen Jesus re-creates these human beings as children of God.
Thus Jesus gives the apostles a holy power to fight against an evil power, a mighty force to do combat with an evil force.
John’s viewpoint challenges modern believers to look beyond “lists of sins” and “new sins” and to view sin as an evil force. The good news is that Christ gives the spirit (or force) to all Christians to do battle against this evil force.