Council of Nicaea (I). My greatx55-grandfather never really understood the whole Arian thing; I remember him telling me as a young boy, "Matthew, I never really understood the whole Arian thing." So there you have it.
Wasn't Nicaea later.... they had a few of those councils.
Go back to the 16th & 17th centuries & the Protestants, particularly the Presbyterians had a good grasp on Arian thinking. I was told thats why the Westlys (sic) & Whitefield started with the Methodist movement (but I wasn't there & I am not related)