#I'm grossly oversimplifying here because I'm by no means an expert on patristics

[ffcrazy15]

I thought that the heresy that person, was the one Saint Nicholas punched Arius for (since someone pointed out that Trinity dogma was established in Nicean synod). And I was like: "Oh, shit, I was talknig the other day about Saint Nick's punch, and now we have Arius 2.0!"

But no, after a short research, it turned out that Arius was more about Jesus not being both a Man and a God, and not about God birthing Jesus etc.

Yup, Arianism was about the hypostatic union, not the nature of the Trinity.

Modalism was condemned by Pope Dionysius under its then-current name "Sabellianism" in Against the Sabellians, AD 262. Trinitarian belief was also explicitly codified in the Nicene Creed at the good old Council of Nicaea in 325.