And we believe in the Holy Spirit, the Lord, the giver of life. He proceeds from the Father and the Son, and with the Father and the Son is worshiped and glorified.
The procession, or spiration, of the Holy Spirit is an eternal procession, with no beginning. And the procession of the Holy Spirit is eternally from the Father and from the Son. It is the Spirit’s procession from the Son that the Eastern Orthodox Church has denied for centuries.
Yet the Scriptural testimony is that the Spirit is not simply the Spirit of the Father, but also the Spirit of Christ.
However, you are not in the flesh but in the Spirit, if indeed the Spirit of God dwells in you. But if anyone does not have the Spirit of Christ, he does not belong to Him. Romans 8:9
Because you are sons, God has sent forth the Spirit of His Son into our hearts, crying, “Abba! Father!” Galatians 4:6
For I know that this shall turn to my salvation through your prayer, and the supply of the Spirit of Jesus Christ Philippians 1:19
Searching what, or what manner of time the Spirit of Christ which was in them did signify, when it testified beforehand the sufferings of Christ, and the glory that should follow. 1 Peter 1:11
To confess that the Holy Spirit eternally proceeds from the Father and from the Son is to confess the unique property of the Spirit, to confess his unique eternal relation to the Father and the Son.
To confess, contrary to the Eastern Orthodox Church, that the Holy Spirit eternally proceeds from the Son, is to confess that he is the all glorious Spirit of Jesus our Lord.
And so says the Second Chapter of the 1644 London Baptist Confession:
That God is of Himself, that is, neither from another, nor of another, nor by another, nor for another: But is a Spirit, who as his being is of Himself, so He gives being, moving, and preservation to all other things, being in Himself eternal, most holy, every way infinite in greatness, wisdom, power, justice, goodness, truth, etc. In this Godhead, there is the Father, the Son, and the Spirit; being every one of them one and the same God; and therefore not divided, but distinguished one from another by their several properties; the Father being from Himself, the Son of the Father from everlasting, the Holy Spirit proceeding from the Father and the Son.
And so says the Second Chapter of the 1689 London Baptist Confession:
In this divine and infinite Being there are three subsistences, the Father, the Word or Son, and Holy Spirit, of one substance, power, and eternity, each having the whole divine essence, yet the essence undivided: the Father is of none, neither begotten nor proceeding; the Son is eternally begotten of the Father; the Holy Spirit proceeding from the Father and the Son; all infinite, without beginning, therefore but one God, who is not to be divided in nature and being, but distinguished by several peculiar relative properties and personal relations; which doctrine of the Trinity is the foundation of all our communion with God, and comfortable dependence on him.