The document discusses the historical context surrounding Constantine and the First Council of Nicaea in 325 CE. It describes Constantine legalizing Christianity with the Edict of Milan in 313 CE and his role in calling the Council of Nicaea to address the Arian heresy and establish orthodox Christian doctrine. The Council defined Jesus as being the same substance as God the Father, rejecting Arianism. Constantine's actions helped establish Christianity as the state religion of the Roman Empire and redefined the political landscape by empowering bishops and the Church.