A Brief History of the Unitarians by Stephen Nye · 1687
[I post this because it traces long before the Socinians, the doctrines they held can be found in history prior to Nicea]
The First Letter, Concerning the Unitarians, vulgarly called Socinians.
SIR,
IN Answer to yours, demanding a brief account of the Unitarians, called also Socinians; their Doctrine concerning God (in which only they differ from other Christians, the Remonstrants, professedly agreeing with them in other points of Faith … Read the rest