One related topic to my last post on the role of the Spirit in salvation is the underlying trinitarian question of whether the Holy Spirit proceeds from the Father or from both the Father and the Son? This issue has been debated for centuries and it was a central reason the Church split in 1054 AD into East and West; the Eastern Church believed the Holy Spirit proceeded from the Father only but the Western Church believed that the Spirit proceeded from Father and Son and inserted the Latin term “filioque” (meaning “and from the Son”) into the Nicene-Constantinopolitan Creed.
Karl Barth argued strongly for the inclusion of the word filioque in the creed, for he believed that his procession from the Son grounded the communion between God and humans:
“The Filioque expresses recognition of the communion between the Father and the Son…. And recognition of this communion is no other than recognition of the basis and confirmation of the communion between God and man as a divine, eternal truth, created in revelation by the Holy Spirit.”
I am quite confident that the Bible teaches filioque in a number of passages (John 15:26, 16:7; Titus 3:5-7; Romans 8:9-10) and so this insight from Barth is a fascinating suggestion regarding the nature of our relationship with God through the Holy Spirit. The Spirit initiates salvation by taking the Word of God (i.e., Jesus, God’s Revelation) and revealing Him compellingly to the human heart (see Ezekiel 36:26-27 and John 3:5-8).
In other words, the procession of the Holy Spirit from Father and Son is directly linked to the Spirit’s vital role in revealing Jesus to believers, securing our salvation. So while it is true that the Spirit (God’s ruach) was at work in creation (Genesis 1:2), and He continues to be at work in God’s providential care of creation (Psalm 104:29-30), the primary, salvific work of the Spirit is to reveal Christ and apply the death/resurrection of Christ to sinners like you and me (cf. 1 Corinthians 2:14).
 Karl Barth, Church Dogmatics as cited by Warren McWIlliams “Why all the Fuss about Filioque? Karl Barth and Jugen Moltmann on the procession of the Spirit” in Perspectives in Religious Studies 22 (1995): 171.
 Contra Clark Pinnock, and thus it is not surprising to learn that Pinnock rejects the addition of the filioque clause. See Ibid., 177.