In Jewish belief, the Shekhinah, or Holy Spirit, is God's active Presence in the world. It is not seen as a separate person. Douglas adds to this a belief in the divinity of Jesus as the Son of God. He believes in the Holy Spirit, he just doesn't see it as a separate person in the Godhead.
You should know not to ask anyone who's been disagreeing with me for three days what doctrine I believe.
I believe that the father and the son make up the Godhead IN HEAVEN. The Holy Spirit is the presence, or power, of the father and/or son, in the creation. The holy spirit IS God's existence in the creation. The difference is that I don't consider it a "person" separate from the father and the son in a triune Godhead in heaven.
In other words, I don't see the Godhead as this:
But kind of like this: