Summary: The addition and acceptance of three words—and the Son (filioque in Latin)—to the Nicene-Constantinopolitan Symbol of Faith (Creed) in the Western Church, and then finally by the Roman See, changed the course of Church and human history. It is often seen as the primordial cause of the dogmatic schism that separated the West from the East a thousand years ago. Here we attempt to unpack the origin and significance of the filioque, and why the Eastern Orthodox Church views it as an assault on the historical doctrine of the Holy Trinity.
