That’s not quite true. It’s really hard to draw a line between these two instituons at Nicaea, because that was an explicitly symbiotic process.
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.
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.