The filioque clause refers to an addition to the Nicene Creed. The phrase "I believe . . . in the Holy Ghost which comes from the Father" was changed to "I believe . . . in the Holy Ghost which comes from the Father and the Son." The Latin word filioque, meaning "and Son," is the source of the name of the filioque clause.
What is the filioque clause/controversy?
At the heart of the controversy is a debate over the sending of the Holy Spirit into the world: was it the Father who sent the Spirit, or the Father and the Son together? The insertion of "and the Son" was such a strong source of contention that it served as part of the theological divide that split the Western Church into the Roman Catholic Church and Eastern Orthodox Church in A.D. 1054. To this day, these two church bodies are in disagreement on this issue.
Several Bible passages have been used to argue that the Holy Spirit proceeds from both the Father and the Son. John 15:26 says, "But when the Helper comes, whom I will send to you from the Father, the Spirit of truth, who proceeds from the Father, he will bear witness about me." In this verse, it is clear that Jesus claims to send the Spirit, and that the Spirit also "goes out" from the Father.
In John 14:26 Jesus says, "But the Helper, the Holy Spirit, whom the Father will send in my name…" Again, both the Father and the Son are involved in the coming of the Holy Spirit. John 14:16 says, "And I will ask the Father, and he will give you another Helper, to be with you forever."
Another consideration is the titles given to the Holy Spirit in the New Testament. He is called "the Spirit of Christ" (Romans 8:9), "the Spirit of Jesus Christ" (Philippians 1:19), and "the Spirit of his Son" (Galatians 4:6). In each case, the Holy Spirit is associated with the Son, a teaching that would support the filioque clause.
Finally, during one of Jesus' post-resurrection appearances, He said to the disciples, "Receive the Holy Spirit" (John 20:22). This seems to plainly state that the Holy Spirit came from the Son. To say the Holy Spirit proceeded from only the Father and not the Son neglects this passage and others or reinterprets them.
While the human mind cannot fully comprehend the relationship among the three Persons of the Trinity, we can look at the words of the Bible. Scripture makes it clear that the Holy Spirit proceeded from both the Father and Son, and so the filioque clause is a plausible way to express the fact.
Who is the Holy Spirit?
When do we receive the Holy Spirit?
What does it mean to be filled with the Holy Spirit?
What is the Trinity?
How is Jesus the Son of God?
Truth about the Holy Spirit