For since one is the Son who also is the living Word: it is necessary that there also be one perfect and full, sanctifying and illuminating, his living power and gift that is said to proceed from the Father, since from the Word, which is conceded to be from the Father, he shines forth, and is sent from the same (Word), and given. Indeed it is most true that the Son is sent from the Father, for he says: "So God loved the world, that he sent his only-begotten Son." (John 3:16) So also the Son sends the Spirit: For "If," he says, "I go, I will send the Paraclete." (John 16:7) The Son likewise honors the Father, as he himself says: "I have glorified Thee." (John 17:4) Likewise the Spirit honors the Son, as the same Son says: "He will glorify me." (John 16:14) The Son moreover says: "What I have heard from the Father, these things I speak in the world." (John 8:26) The Spirit, however, also receives from the Son. "Of mine," he says, "he will receive and he will announce to you." (John 16:14) Likewise, the Son comes in the name of the Father. So also "the Holy Spirit," the Son says, "whom the Father will send in my name." (John 14:26)When therefore the Spirit has the same order and the same nature with respect to the Son, as the Son has to the Father, by what reason, I ask, does he who contends that the holy Spirit is a created thing, not likewise necessarily think the same of the Son? (St. Athanasius, First Letter to Serapion: Against those who blaspheme and say that the holy Spirit is a created thing, P.G. 26:579A-B, my translation)
Far greater minds, Latin Catholic and Orthodox, than ours, friend, dealt with this issue for 4 years and just two years ago in DC, wrote quite a statement on the matter. Here's a link. Its four pages long but worth the read. The bottome line is, the Latin Rite Catholic theologians agreed with the Orthodox that the Creed without the filioque is normative. Here's a link: http://www.scoba.us/resources/filioque-p01.asp