In addition, the entire Holy Orthodox Church agreed on the Creed. Nicaea decided that Creed and anathemas were attached to anyone adding or deleting a word of it. Whether Augustine “got it” or not, that Creed was not to be touched.
I don’t buy this argument for the sole fact that the Orthodox Church DID change the Creed - the original creed was in first person plural, and the Eastern Orthodox Churches use the first person singular, and the fact that nobody seems to care that the Latins changed “essence” to “substance” or added “God from God,” or how the Coptics added “Yes” before the “We believe in the Holy Spirit,”
It seems to me that the proper reading of Nicaea is that the Faith of the Creed cannot be changed - and in my humble opinion, I don’t think the Filioque insertion was heretical until Charlemagne declared in a local council that the Byzantines removed the Filioque from the Creed and have deviated from the Faith - an absolute lie, of course, but it would be repeated by Cardinal Humbert when he excommunicated Michael Celuarius.
I’m personally siding with Saint Maximos the Confessor, who said this:
“With regard to the first matter, they (the Romans) have produced the unanimous documentary evidence of the Latin fathers, and also of Cyril of Alexandria, from the sacred commentary he composed on the gospel of St. John. On the basis of these texts, they have shown that they have not made the Son the cause of the Spirit — they know in fact that the Father is the only cause of the Son and the Spirit, the one by begetting and the other by procession; but [they use this expression] in order to manifest the Spirit’s coming-forth (προϊέναι) through him and, in this way, to make clear the unity and identity of the essence….
The Romans have therefore been accused of things of which it is wrong to accuse them, whereas of the things of which the Byzantines have quite rightly been accused (viz., Monothelitism), they have, to date, made no self-defense, because neither have they gotten rid of the things introduced by them.
But, in accordance with your request, I have asked the Romans to translate what is peculiar to them in such a way that any obscurities that may result from it will be avoided. But since the practice of writing and sending (the synodal letters) has been observed, I wonder whether they will possibly agree to doing this. One should also keep in mind that they cannot express their meaning in a language and idiom that are foreign to them as precisely as they can in their own mother-tongue, any more than we can do.”
Unfortunately Florence declared this very thing, that the Son is the Cause of the Spirit, and that they believe the Spirit proceeds from the Son identically to how it does from the Father.
I don’t mind correction, but based on me studying it, those are my two cents.