State persecution ceased in the 4th century, when Constantine I issued an edict of toleration in 313. On 27 February 380, Emperor Theodosius I enacted a law establishing Nicene Christianity as the state church of the Roman Empire. From at least the 4th century, Christianity has played a prominent role in the shaping of Western civilization. Constantine was also instrumental in the convocation of the First Council of Nicaea in 325, which sought to address the Arian heresy and formulated the Nicene Creed, which is still used by Anglican Communion and many Protestant churches, the Catholic Church and Eastern Orthodoxy, . Nicaea was the first of a series of Ecumenical (worldwide) Councils which formally defined critical elements of the theology of the Church, notably concerning Christology. The Assyrian Church of the East did not accept the third and following Ecumenical Councils, and are still separate today. In 395, the most Christianized regions of the world were Crete, Cyprus, Anatolia, Armenia, the Nile delta, and Numidia (present-day Tunisia and Algeria). The presence of Christianity in Africa began in the middle of the 1st century in Egypt, and by the end of the 2nd century in the region around Carthage. Mark the Evangelist started the Orthodox Church of Alexandria in about 43 AD. Important Africans who influenced the early development of Christianity includes Tertullian, Clement of Alexandria, Origen of Alexandria, Cyprian, Athanasius and Augustine of Hippo. The later rise of Islam in North Africa reduced the size and numbers of Christian congregations, leaving only the Coptic Church in Egypt, the Ethiopian Orthodox Tewahedo Church in the Horn of Africa, and the Nubian Church in the Sudan (Nobatia, Makuria, and Alodia).