The whole issue with the Council of Florence becomes easier to understand when you realize one of the men who torpedoed its implementation was not even a Christian. Gemistus Plethon was at Florence where he helped to prevent its implementation on strict Hellenistic idealism.
Gemistus Plethon was a Neoplatonic philosopher in Constantinople who kept the most extensive library of Plato in the world at the time. He idealized Plato enough to change his name to Plethon which came from the same Greek word.
He was born a Greek Orthodox Christian but began to believe in more heretical ideas until he left Christianity all together for neopaganism. He worshipped the ancient Olympian gods and believed Christianity had destroyed the Roman Empire and taken away Hellenic excellence
Plethon had studied in Edirne the capital of the Ottoman Empire and the once Greek city of Adrianople. He saw the Muslim and Semitic (modeled on Baghdad and Damascus) takeover of the city as a sign of the rot of Abrahamism destroying Hellenic beauty and truth.
Somehow because he was very intelligent and the worlds foremost expert on Plato Gemistus Plethon gained the ear of the Emperor and was for some reason brought to a Church Council despite hating Christianity and not being a Christian.
Gemistus Plethon initially supported the idea but only for the reason that he was eager for Western soldiers and money to rebuild Hellas and fight off the Turks. Until he got to Italy and met Italians at which point he considered them Barbarians far removed from Roman glory.
Plethon blamed Christianity and was a big fan of Emperor Julian the Apostate. He read Against the Galileans by Julian. Plethon’s own beliefs were heavily influenced by Julian. He believed in the pantheon of Hellenic gods but in a different conception than the Classical Greeks.
It was at Florence that Gemistus Plethon turned against the idea of reunion because he didnt want the Westerners to ruin his ideal Hellenic society. He thought that the Latins arguing at Florence were so stupid and incompetent. Their reliance on Aristotle he felt was elementary.
While he was in Italy, Gemistus Plethon met many Florentine nobles and gave lectures on Platonism and Hellenism. His main student was Cosimo de Medici. Cosimo de Medici became a devoted Platonist and opened and school in Florence to teach Platonism and Hellenic esoterica.
Plethon gave de Medici several books on Hermeticism and Eastern Occultism. This was translated at the school into Latin as the Corpus Hermeticum. Single handedly reintroducing Italy to pagan mysticism and religious ideas which were explicitly non-Christian. Many of the students of the Platonic school in Florence apostacized from the Church and began worshipping these pagan gods in secret. Many were devoted followers of Hermes Trismegistus including the de Medici family.
When Gemistus Plethon returned to Greece and to Morea Greece, he wrote a treatise on the reorganization of Greek society from the Byzantine model to a model of government based on ancient Sparta with a native Greek warrior class and Helot slaves.
He presented these ideas to the Despot of Morea who rejected them, but Plethon’s more insidious influence came from the fact he was a government official and influenced people that the Westerners were dumb Barbarians and anything to do with them was bad.
He helped keep the Byzantine rump state from embracing Western help and from reunion with the Catholic Church. Gemistus Plethon died in 1454 living just long enough to see Constantinople fall. He lived his whole life clinging to the delusion of Hellenic revivalism and paganism
Plethon’s influence on Renaissance Italy was all bad. He started the trend of Renaissance pagan cults and secret societies in Italy. He contributed immensely to apostasy and heresy among many, even Bishops. His students became devotees who revered him as a prophet. Ultimately, we can largely blame Gemistus Plethon for the Enlightenment and the apostasy of so many in Christian societies from Christianity today, as well as the proliferation of Masonic organizations and secret societies worshipping pagan gods and practicing Hermeticism.