The Filioque controversy is the central disagreement of the Latin (Roman Catholic) and Greek (including the Eastern Orthodox) church. It refers to a small addition to the Nicene Creed that says the Procession of the Holy Spirit comes from both the Father and Son, though the translation and understanding of this can be confusing. The Roman Catholic Church supports this addition and the idea that the Holy Spirit come from the Son and Father; the Greek/Eastern tradition claims this is a heresy, and that the Holy Spirit comes from the father alone.
The Original Greek phrasing of the Nicene Creed did not include the phrase ‘and the Son’ (Filioque) regarding the Holy Spirit processing from the Father. The phrase ‘and the Son’ was added in the Latin version, understood to be in accordance with official doctrine and tradition. It was noted that differences between the Latin and Greek language prevented the phrase from being correctly understood when the Nicene Creed was written in Greek. This was understood as the reason why the phrase was not originally included in the Greek version, and why it remains left out to the Greek translation to this day. Supporters of either sides of the theological debate leave out the extra phrase when the Nicene Creed is written or spoken in Greek.
The Roman Catholic position holds that the Procession of the Holy Spirit is from the Father through the Son. It hold that this procession is not from two principles (Father and Son), but from one single principle. Language and translation problems prevent this from being expressed clearly in Greek, where the addition of the phrase ‘and the Son’ would misleadingly indicate the Holy Spirit comes from the two principles, the Father and the Son. The phrase ‘and the Son’ is added in Latin version of the creed as it does not cause this misunderstanding.
The Eastern Orthodox Church holds that the procession of the Holy Spirit come through the Father alone, a single principle. This is a matter of theology, and they believe the Greek version of the Nicene Creed reflects this theology. The matter is not thought to be caused by any confusion over the Greek language; the Greek version of the Nicene Creed is accurate as it stands.
Protestant views vary, but the protestant split from the Catholic Church was not concerned with any disagreement over the Nicene Creed. There is no tradition based reason why the protestant churches should support either side of this debate. Ecumenical based thinkers have suggested leaving the ‘and the Son’ clause out in order to avoid disagreements and unite different denominations.
The debate about inclusion of the ‘and the Son’ phrase is a matter of either theology of the relationship within the trinity or a matter of semantics. If the language/semantics is the issue it is possible that the two sides of the debate disagree because they are discussing different things. This suggests reconciliation is possible through appropriate doctrine understanding and translation. Even if the matter is a legitimate theological issue it probably has minimal influence on the general Christian believer, despite all the debate. Both sides believe in the Procession of the Holy Spirit and the influence on the life of each Christian believer. Both sides believe the Holy Spirit is part of the Holy Trinity. Most individuals are not concerned with distinguishing details beyond this.