More thoughts on April’s book of the Month The Holy Spirit, by Sinclair Ferguson…
As we saw in the last post, Ferguson’s book on the Holy Spirit is so helpful and valuable because he does not merely camp out on the subject of tongues and miracles and various spiritual gifts, but rather He provides a foundational study on what the Scriptures teach concerning the Third Person of the Trinity. We cannot answer questions about modern day manifestations of the Spirit’s work unless we first understand who He is and what His function is in the Godhead and the Church.
Having done that work, Ferguson then proceeds to explain exactly why the Great Schism between the Western and Eastern churches that took place in 1054 was not a silly split over theological minutiae, but was in fact a “really big deal” that continues to matter.
The question at the heart of the controversy in 1054 concerned whether the Nicene Creed was correct in affirming that the Spirit proceeded from the Father and the Son (which has been referred to through history as the “Filioque” clause, abbreviated from the Latin “a Patre Filioque” translated “from the Father and the Son”), and whether it would be more correct to state that the Spirit proceeded from the Father only. The Eastern church took the latter position, while the Western church pointed to the fact that Jesus clearly states that He is the one sending the Spirit “from the Father” (John 15:26). The Spirit thus goes on His mission from the Father and from the Son.
Ferguson recognizes that most modern Christians have little time or energy to expend on subtle theological distinctions made in a theological controversy a thousand years ago, and even those Christians who do actually care still might not be able to see through all of the cultural and societal issues that clouded the debate. Yet it is good for us to understand exactly why the right answer to this question is still important to the modern Church.
Simply stated, if we have a doctrine of the Spirit that is divorced from our doctrine of Jesus, and if indeed the Spirit is not sent by the Son, but only by the Father, then the Church has a relationship with the Spirit that is somehow separated from and different from her relationship with the Son, her Lord and Head. It implies that we can have a relationship with God the Father through the Spirit that does not take into account the Word Made Flesh and the articulation of the will of the Father through the words and deeds of the person of Jesus Christ.
If this were true, then the only direction the Church would have to go from there in its doctrine of the Spirit is into a territory outside of the bounds of the Word and Sacrament – a direction the Eastern Church has certainly gone for the last millennium, and has ended up losing herself in her own world of mysticism and superstition.
However, knowing that the Spirit is sent by the Father through the Son provides further insights into the inner workings of the union and communion of the Trinity and our place in that relationship as the Spirit wraps us into the love of the Father and the Son.
 Ferguson pg. 72-73, 77