of Constantine, was a Christian and has been canonized by the church.  When Constantine marched against his rival, he took for his ensign a standard (the labarum), which bore the cross and the monogram of Christ.  His victory was the victory of the Christians.  He allowed them now to perform their religious rites freely (by the edict of 313), and later he favored them openly.  Yet he did not break with the ancient religion:  while he presided at the great assembly of the Christian bishops, he continued to hold the title of Pontifex Maximus; he carried in his helmet a nail of the true cross and on his coins he still had the sun-god represented.  In his city of Constantinople he had a Christian church built, but also a temple to Victory.  For a half-century it was difficult to know what was the official religion of the empire.

=Organization of the Church.=—­The Christians even under persecution had never dreamed of overthrowing the empire.  As soon as persecution ceased, the bishops became the allies of the emperors.  Then the Christian church was organized definitively, and it was organized on the model of the Later Empire, in the form that it preserves to this day.  Each city had a bishop who resided in the city proper and governed the people of the territory; this territory subject to the bishop was termed a Diocese.  In any country in the Later Empire, there were as many bishops and dioceses as there were cities.  This is why the bishops were so numerous and dioceses so many in the East and in Italy where the country was covered with cities.  In Gaul, on the contrary, there were but 120 dioceses between the Rhine and the Pyrenees, and the most of these, save in the south, were of the size of a modern French department.  Each province became an ecclesiastical province; the bishop of the capital (metropolis) became the metropolitan, or as he was later termed, the archbishop.

=The Councils.=—­In this century began the councils, the great assemblies of the church.  There had already been some local councils at which the bishops and priests of a single province had been present.  For the first time, in 324,[175] Constantine convoked a General Assembly of the World (an ecumenical council) at Nicaea, in Asia Minor; 318 ecclesiastics were in attendance.  They discussed questions of theology and drew up the Nicene Creed, the Catholic confession of faith.  Then the emperor wrote to all the churches, bidding them “conform to the will of God as expressed by the council.”  This was the first ecumenical council, and there were three others[176] of these before the arrival of the barbarians made an assembly of the whole church impossible.  The decisions reached by these councils had the force of law for all Christians:  the decisions are called Canons[177] (rules).  The collection of these regulations constitutes the Canon Law.