Ummm ... no. Secodn Ecumenical Council.
The Latin-Greek split or schism before, during, and after the Fourth Crusade led to the theory that the Roman Catholic Church has one bishop ( the Pope ), and all the other bishops are in essence his local representatives.
Well, that isn't really the Catholic view, but lets not quibble over that. The same theory that is attempting to be propounded here (primacy of the Bishop of Rome) is found in kernel form in the letters of Pope St. Cornelius and St. Cyrpian of Carthage circa AD 250.
The alteration of the original Creed occurred some time in the sixth or seventh century in Spain probably by mistake, for the Spanish Church had few men of learning in those early centuries.
The men who added it to the Creed in Spain were among the most learned in all the West, who produced the mangificent creedal statements of the Councils of Toledo. They were following in the common teaching of the west what your Fr. Romanides has termed the "Western Orthodox filioque" to show that he felt it was not heretical) as asserted by Sts. Amrbose, Augustine, Leo, and others. The earliest citation in a Creed out of Toledo is from AD 447. The west, of course, did not even recognize Constantinople II as an ecumenical council until the ratification of Chalcedon in AD 451. Witness the lack of citation of the creed at Ephesus, which knew only of Nicea.
Ergo, pillaging, raping, killing, in the name of the Church and Pope.
The Pope had prior to this point excommunicated the Crusaders after they fell upon Zadar on the Dalmatian Coast. They were of course spurred on to Constatinople by the pretender to the East Roman throne, in whose pay they were operating.
These type of little mistakes make it difficult to trust larger assertions.
Following the tragic event of July 16,1054, when cardinal Humbert entered Hagia Sophia and immediately before the Divine Liturgy placed a bull of excommunication on the Altar, on behalf of the deceased pope Leo IX, things went from bad to worse when in 1071, the Normans conquered Bari (Italy), the last remaining Byzantine possession in Italy. By that time, the Byzantine Empire found itself unable to defend its land even closer than Italy. They were unable to cope with the double invasion that swept the empire – by the Patzinaks from across the Danube and by the Turks from the heart of Asia Minor. In 1071 they defeated and captured Emperor Romanos IV in the tragic battle of Manzikert. The loss of Bari and defeat at Manzikert in the same year indicated the condition of the Empire. In 1071 Jerusalem and the Holy Sepulchre also passed into Turkish hands for the 1st. time.
You would think someone might see the Hand of God in all this.