What in the world is the Holy Spirit?
The Holy Spirit (pneuma, πνεύμα) is part of the Trinity, and asserted in the Nicene Creed. “I believe in the Holy Spirit.” But I think the Holy Spirit gets short shrift, and almost always comes last in the trio: God the father, God the Son, and God the Holy Spirit. I think I know (as far as an ordinary human can) what God is, and who Christ is. I’m just not sure about the Holy Spirit.
The Holy Spirit seems to be an inspirational force that took the place of Christ after his death. It explains how a bunch of cowardly and disorganized apostles who fled the scene after Christ’s execution could, fifty days after his crucifixion, become the highly motivated and organized group who created Christianity. The Holy Spirit remains with us today; it’s part of believing in God and Jesus. If you believe in Jesus, then you believe in the Holy Spirit, so it’s worthwhile figuring out what it might be.