John S. Feinberg
There are also passages that teach that the Son and the Spirit are one. In Rom. 8:910 Paul speaks of the indwelling of the Holy Spirit, but he says that anyone who does not have the Holy Spirit does not belong to Christ. Thus, in having Christ, one also has the Holy Spirit and vice versa. All of this suggests their unity. Moreover, consider 2 Cor 3:17. As we have already seen, this verse says that the Lord is the Spirit, and the word for Lord is kyrios, the Greek for the Hebrew yhwh. Many see kyrios here as a reference to Jesus who, of course, is often called by this name. In that case, the verse asserts unity between the Son and the Spirit.
John S. Feinberg, No One Like Him (Wheaton, IL: Crossway Books, 2001), p. 467