One Iota: Homoiousios and Homoousioshomoiousios (ηομοιουσιος), meaning “of a similar substance,” and homoousios (ηομοουσιος), meaning “of the same substance”; two words that differ by a single letter: iota. In fact, in his “History of Christianity,” Edward Gibbon pointed out, with some ridicule, that Christianity was nearly split by the smallest letter in the Greek alphabet.
In Alexandria around the year 319, the previously obscure presbyter Arius attempted to rationalize the mystery that Chrisitians find in the relationship between Jesus and God. He attracted a large following preaching the neoplatonist idea of the absolute oneness of the divinity. He felt that this was a unity that could not be shared, and therefore Jesus was a lesser deity who had been called into existance by God. Jesus was “homoiousian,” that is, of a similar nature to God, but not the same as, God.
Opponents, led most promenently by Athanasius, bishop of Alexandria, preached that Jesus was in fact “homoousian,” the same as God. This caused such conflict that Emporer Constantine demanded they work out their differences at what became the Council of Nicaea in 325.
The homoosians won the debate and codified their beliefs in a set of statements known as the original Nicene Creed, which states that Jesus is “one in being” with the Father. A version of the creed is still recited at mass by Catholics to this day.