Divine Thoughts? On the Holy Spirit

When people find out that I'm a student of theology at the PhD level, they tend to start coming to me with a lot of questions. One of the most basic--and the most fun, as a pentecostal Christian--is, "Who or what is the Holy Spirit?" As with most good questions, there are various levels of complexity. I usually give two:

1. "The Holy Spirit is God/God is the Holy Spirit."
2. "The Holy Spirit is the third Person of the Truine God."

But what does this mean? Doesn't using this language confuse people? Isn't there only one God? Besides, why would Christians use a word that's not even in the Bible as shorthand?

Judaism has always affirmed that there is one God, the Creator of All. He revealed Himself (the gender pronoun is for convenience) as YHWH (Yahweh) or "the LORD," the God of Abraham, Isaac, and Jacob. (Whether or not ancient Israelite religion made this affirmation is a matter of ongoing debate!)

The One God made His presence known through Israel's worship, through the giving of the Torah, through the extraordinary empowerment (by the "Spirit of Yahweh") of kings, priests, and prophets, by His faithfulness in bringing his people Israel back from exile & idolatry. (Idolatry is putting something YHWH created in YHWH's place, as though it is worthy of worship, even though the One God created it!)

From very early on in the Christian movement, the followers of Jesus recognized that not only was Jesus the Messiah (anointed one) sent by this God to free His people, but also the very Presence of that God as a human being. Christians believe that Jesus did all the sorts of things that Yahweh would do if he were standing on the earth running the show: bringing healing (shalom) to bodies, relationships, even nature itself; and challenging spiritual beings and political powers-that-be that would try to prevent true peace.

But paradoxically, Jesus referred to God as Father, implying a distinction even within the Oneness of Godself. Jesus promised that after he was crucified and raised from the dead, he would send the Paraclete, or Teacher, one who would comfort, advocate for, and empower his followers after Jesus was crucified and raised by God from the dead. Christians (originally called "followers of the Way") quickly realised that this same Spirit sent by Jesus was, again, the same Presence that they recognized as Jesus' Father and Jesus himself. When they looked for confirmation of this in their Scriptures, they found that wherever the One True and Faithful God was working, so was the Spirit.

One of the Church Fathers who was defending the deity of the Spirit while the Church worked it out said: "Is there anything excellent in the idea of God that is beyond the Spirit's power?" The Church concluded, after about fifty years of official debate, that the Spirit was best spoken of as God, too. (Working out what that meant fully took much longer.)