Complex sentence: Various forms of subordinationism were believed by some in early Christianity until the mid 4th century, when the Arian controversy was settled, after many decades of formulating of the doctrine of Trinity, by the First Council of Constantinople in 381 which condemned Arianism.
Split into simpler sentences: Various forms of subordinationism were either believed or condemned in until the mid 4th century, when the debate was settled against subordinationism, as part of the Arian controversy. After many decades of formulating of the doctrine of Trinity, by the First Council of Constantinople in 381 which condemned Arianism.