> Mount Vesuvius’ pyroclastic flows and poisonous fumes killed around 2,000 people in Pompeii and the neighboring city of Herculaneum.
The time period of Secundio's tomb is around AD 60 or so. As the article at pompeiisites.org says, "During the Roman period at Pompeii, funeral rites usually involved cremation, while only small children were buried." This burial of a 60 year old man stands out for a few reasons, but one of which is that it even exists at all given that it's contrary to custom of the pre-Christian age.
The Roman Empire didn't codify anything. The Nicene Creed was composed by the Church in response to the Arian crisis. That the empire (through Constantine) had an interest in peace does not mean the empire performed the clarification.
First of all, the council was summoned by the emperor, organized by him, paid for by him, facilitated using public infrastructure, and personally attended by him. He might have “deferred” to the decisions of the bishops, but only happens when everyone recognizes his power to just declare things. He also banished some of the losing bishops into exile using his personal power. Whether or not it’s the “empire” or the dictatorial emperor declaring a thing is a fuzzy line, but a lot of state power was involved.
Secondly it wasn’t “the church” who declared anything, because no such singular institution actually existed to speak with one voice. Rather, the council was a self-conscious effort by Constantine to actually create a unified church, since he worried that the existing discord threatened spiritual safety of the church. Remember that Christianity had been legal for only a decade or so and it would take a while before the more underground organization could organize and finish settling old scores. Whether or not the Bishop of Rome was recognized as the leader of the church is still a hotly debated subject; he however did not actually chair the council of Nicaea. At Nicaea we’re still a century or two out from the first papal bull, 400 years or so from the first cardinals, and 700 years from the first recognizably modern papal conclave. In any case, only 300 or so of the 1,800 bishops of the empire attended.
In many ways the church became The Church by taking over the mantle of imperial authority as the Roman Empire receded from Western Europe. This is the process that gives it the power, organization, and bureaucracy to set religious policy and speak in one voice, and none of that is in place by Nicaea.
Rome was very serious about worshiping Ceasar; the rest was optional.
(Rome didn't have a "civil society" or "social contract" in any sense we'd recognize. Their laws were supposed to be divinely ordained, and refusing to acknowledge this was grounds for the death penalty. If you're imagining Rome as some sort of freedom of religion place like America with the First Amendment then you're sorely mistaken; think Soviet communism or China instead.)
Your parallels to 20th century governments miss the mark as much as the claims you are criticizing.
On a more serious note, I wonder how people reacted to his decision to forgo cremation at the time, especially since he is a priest himself; and if there were any discussions, even privately among his relatives, on how he can get away with it because of his status (if this was really the case).
It's for moment like these, not the ones immortalized by historians, that I wish there is/was (does it even matter what tense to use) a time machine.