2. It introduced arbitrary theology. Since the only static, nonambiguous datapoint in scripture is when Jesus says, "the spirit, who proceeds from the father", all other scriptural datapoints are secondary inferences of procession based on the temporal mission of the holy spirit. Ie, the Son sends the Spirit in time as an indication of the eternal procession of the Spirit. But this requires first that it is true that a temporal sending is indicative of eternal procession, and there is no scriptural reason to assume that is true. Its arbitrarily asserted. Furthermore, the same type of evidence, which is inference of procession based on temporal mission could be made equally to say the Father and the Spirit eternally beget the Son. Why? Because in time, the Spirit begets the Son in the virgin birth. The Spirit acts on the Son at his baptism. "The Spirit is upon me to preach the good news...".. So if one divine Person acting on another in time is indicative of eternal procession, then an equally strong case can be made to say the Father and the Spirit eternally beget the Son. The "Spirituque"... but no one makes his argument. The Filioque argument is made by motivated reasoning to bolster the position of the Son to combat Arianism. Its assertion from the data is arbitrary if the same case can be made in the opposite. Lastly, certain scholastics have made analogies based on the Son breathing the Spirit on the disciples as an indication of the procession, the Spirit/Breath/Wind/Ruach comes out of the Son... but if we admit these analogies, it must also be admitted that Words (the Son is the Word) are created by Breath/Ruach, so the Son would proceed from the Spirit. Again, its arbitrary which side you choose. Arbitrary theological precepts destroy a focus on truth, and without Truth, Christianity is destroyed. If we allow arbitrary theology, that can be introduced via papal fiat or personal conscience (protestant), theology is completely unmoored, destroying Christianity itself.