I recently spent several hours trying to convince a class that Arius was right, the Son is not equal with the Father, and Athanasius blew it.
So we looked at all the biblical data suggesting that the Son is subordinate to the Father. We discussed Greek philosophy and how the Nicene view of three persons (hypostases) in one substance (ousia) necessarily entails either modalism–i.e. the one substance (God) just manifested himself at different times as different persons (Father, Son, and Spirit)–or tritheism–i.e. the one substance (deity) gets expressed in three distinct beings (Father, Son, and Spirit) just like our one human nature gets expressed as many particular humans. And, most importantly, we talked about the Cross, how Athanasius’ overly divine Son downplays the real human suffering on the cross that is a necessary part of any true atonement.
In short, we presented a pretty compelling argument for the truth of Arianism. Indeed, when we were done and had summarized all the strongest arguments for Arianism on the board, I asked the class to refute them. And they were stuck. They still felt intuitively that Arianism had to be wrong, but they couldn’t find the chinks in the armor. It looked so compelling.
That’s when I knew we’d arrived.