First Council of Nicaea: when Christianity was deformed and Jesus named son of God.

[WinterHold]

Heresy according to whom? emperor Constantine and his priests? 
This was a filtration of the Roman religious institution from any opposing voice ! the belief that Jesus is a mere prophet was "normal" and even "accepted by many" across the empire:

https://www.britannica.com/topic/Arianism



The real heresy is the act of Constantine and his priests.
Nobody saw Jesus as a son of God but the "heretic" Constantine and his priests; he doomed his empire and produced a mutant heathen.

He produced "a trinity".

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Read history better, please.

It’s definitional. You can’t reasonably argue that a heterodox religious position is anything BUT heresy. Bear it mind that declaring a belief to be heretical doesn’t establish which belief is correct, only that the minority position is seen as a threat to the majority. And the Arians were decidedly in the minority. As I’ve told you before, the belief you call ‘Nicene Christianity’ was the majority position of most Christians before the Council ever took place. If you have actual evidence to the contrary, I’ll be happy to consider it.

Boru

Heterodox religious beliefs were always present in Christianity; even the NT  had a heterodox sections that were "filtered" and "rejected" by the religious institution:

a list of the books of Holy Scripture was drawn up,[9] and these books (including some considered apocryphal by Protestants) are still regarded as the constituents of the Catholic canon. 

https://en.wikipedia.org/wiki/Hippo_Regi...l_of_Hippo
Are Catholics "heretics" or are Protestants are "heretics"?
As I said it will end in bloodshed.