So the fact that Diocletian's palace had a Christian basilica across from it means the Church was still underground? How does that work exactly? 15% of the Empire's population was Christian by the time of Diocletian, nevermind the overwhelming majority of sympathizers it found with the "godfearers" of the day. It is simply not true that Christianity was persecuted nonstop until Constantine.
Of course Nicea didn't introduce anything new as regards the Divinity of Our Lord, but the word homoousios as it is understood today did come from Nicea. If everything was spelled out so well in Sacred Scripture, why was a council needed to combat Arianism?
I hope this isn't going to turn into a debate with a website.
You mean the Great Persecution under Diocletian between AD 303 and 313?