Q&A website quote:
The essential matter in the filioque clause is a desire to protect the deity of the Holy Spirit. The Bible clearly teaches that the Holy Spirit is God (Acts 5:3-4). Those who oppose the filioque clause object because they believe the Holy Spirit proceeding from the Father and the Son makes the Holy Spirit subservient to the Father and Son. Those who uphold the filioque clause believe that the Holy Spirit proceeding from both the Father and the Son does not impact the Spirit being equally God with the Father and the Son.
The filioque clause controversy likely involves an aspect of God’s person that we will never be able to fully grasp. God, who is an infinite being, is ultimately incomprehensible to our finite human minds. The Holy Spirit is God, and He was sent by God as Jesus Christ’s replacement here on earth. The question of whether the Holy Spirit was sent by the Father, or by the Father and the Son, likely cannot be decisively answered, nor does it absolutely need to be. The filioque clause will perhaps have to remain a controversy.
I sure don’t believe that the Holy Spirit is unequal. But, I’m from the bygone days when He was called the HOLY GHOST.