The controversy of the filioque focused on the relationship of the Holy Spirit of the Father and the Son. The Eastern Church rejected the term because it makes Jesus Christ a creator similar to God. It further refutes further refutes Arianism because it makes the Father and the Son equal.
The filioque succeeded in the Western Church and resulted in the split of the Western and Eastern Churches. The Orthodox Christian theologians were concerned about calling the Spirit “God” because it was not originally stated in scripture and they were uncomfortable with this idea.