Marked by the legalization of Christianity under Emperor Constantine (Edict of Milan, 313 AD), this period saw the Church gain imperial support. The Council of Nicaea (325 AD) addressed the Arian heresy, affirming the divinity of Christ in the Nicene Creed. Later councils (e.g., Constantinople, Chalcedon) further defined Trinitarian and Christological doctrines. Church Fathers like Augustine shaped theology, while monasticism emerged.
Letter of Eusebius of Coesarea to the people of his Diocese . 1. What was transacted concerning ecclesiastical faith at the Great Council assembled at Nicaea, you have probably learned, Beloved, from other sources, rumour being wont to precede the…