Church History:  The 300s


What happened in this century?

  • At the beginning:  Persecutions end and Christianity is legalized.

  • At the end:  Christianity is the official religion of the Roman Empire.

  • The first two major Councils, Nicaea and Constantinople, are convened.

  • The 27 books of the New Testament are accepted and the canon (Scripture) is closed.

  • By the end of this century, the Canon, Creed, and Clergy of Christianity has been established.

Contact Mark Nickens, Ph.D. in Church History, at  Questions, comments, and observations are welcome.


2009-2011 Mark Nickens


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Sometime in the 300s        Sinaiticus, the oldest complete copy of the NT, dates from the 300s.


More Info:  The Sinaiticus almost became part of a fire to heat a stove.  Find out the fascinating story here.


303        The Emperor Diocletian began a persecution of the Christians, who had become quite numerous by this time.  He ordered that all churches be burned (this could have included house churches, which could have meant that people's homes were destroyed) and all Christian Scriptures be burned.  Eusebius (b. 260 and therefore an eyewitness) wrote "We saw with our very eyes . . . the inspired and sacred scriptures committed to the flames in the marketplaces."  (Church History 8.2.1)


304        Pope Marcellinus died.  Due to the Diocletian persecution and the havoc it caused, no one would ascend to the papacy until 308.


306        The earliest known record which enforces celibacy of clergy dates from the Council of Elvira held in this year.  The clergy were assumed to be married but were commanded "to abstain completely from their wives and not have children."  See bibliography for source of quote.


309        Marcellus I died and Eusebius of Cassano became Pope; four months later he died and no one ascended to the papacy until 311.


311        The Emperor Galerius issued an Edict of Toleration toward the Christians as he lay dying.  Apparently he was so afraid of dying that he included this request:  "In return for our tolerance, Christians will be required to pray to their god for us." He died five days later. 


313        The Edict of Milan is signed by co-emperors Constantine and Licinius and ends persecutions of Christians.  It states in part, ""We therefore announce that, notwithstanding any provisions concerning the Christians in our former instructions, all who choose that religion are to be permitted to continue therein, without any let or hindrance, and are not to be in any way troubled or molested."  In 380, Christianity would become the official religion of the Roman Empire.


More info:  To read a short history of the Christian persecutions, click here.


314        The Synod of Arles was commissioned by Constantine to respond to the Donatist schism.  This schism resulted over the question of how to respond to priests who had buckled under persecution.  To learn more about the Donatist schism and its result, go here.


315        Forty Christian soldiers are martyred by being placed on a frozen lake.  Read how thirty-nine of the martyrs convinced one soldier to join them; click here.


320        Pachomius established the first monastery in the Egyptian desert.  This type of monasticism is known as cenobitic (or coebobitic) monasticism.  Pachomius wrote a set of rules to guide the monks at his monasteries, known as a Rule.  To read his rule, go to  To learn more about Pachomius, how he had to restart his monastery, and why it was more successful the second time, click here.


The Big Picture:  Creation of Monasticism

The Catholic, Orthodox, and Episcopal Churches all have monks and nuns, which began with the Egyptian desert monks, and to a lesser degree Syria.  The answer to the question of why people began to withdraw into the desert cannot be fully satisfied.  Part of the reason includes a discontent with Christian as it became more widely accepted and mainstream, the availability of a large space (the desert) which could be readily accessed and where one could be isolated (unlike in southern Europe), and a desire to fully surrender to God in an age when persecutions had ended (you could no longer be put to death for being a Christian after but you could die to yourself in the form of being a monk or nun).  The two monks given credit for initiating the two types of monasticism, solitary or eremitic and communal or cenobitic, are Antony (see the year 285; eremitic) and Pachomius (see the year 320; cenobitic).  These monks left a number of sayings behind; click below for three compilations.


More info:  A number of sayings of the desert fathers from this time period exist.  Click here:  one, two, three.


324        Constantine became the sole ruler of the Roman Empire, having defeated Licinius.


325        The Emperor Constantine called the Council of Nicaea (or Nicea), which is known as the First Ecumenical Council; this refers to the fact that it called all Christian leaders to gather together for the first time.  This was the first of the twenty-one major Church Councils.  Councils or meetings had been held before between several or a number of leaders, but this was the first one to include all Christian leaders.  Around 300 Christian leaders attended from near and far; one "John of Persia" signed his name and wrote that he was head of all churches in Persia and India.    One issue dealt with in the Council was a debate initiated by Arius, who denied the divinity of Jesus.  Arius believed that Jesus was created by God and was therefore not eternal nor divine (on the same level as the Father).  The debate was reduced to a chose of words:  should the word "homoousios" (of the same nature) or "homoiousios" (of the similar or like nature; preferred by the Arians) be used to describe Christ; the former was chosen.  The Nicene Creed developed within the Council to defeat Arius' thought.  Arius, who attended, refused to sign the Creed.  To read the Creed including the portion  which ostracized the Arians, click here.  The Creed would be enlarged at the Council of Constantinople in 381.  See that year to read the Creed.


More info:  One of the decisions at the Council was the dating of Easter.  To read more, click here.


326        Helena, the mother of Constantine, visited the Holy Land.  She had basilicas built on the Mount of Olives and in Bethlehem.   The basilica in Bethlehem was destroyed in 529 and rebuilt in 565 and is today known as the Church of the Nativity.  Some believe the birthplace of Jesus is located inside it.   She also supposedly brought back to Rome the 28 steps in Herod's palace which Jesus walked up to be put on trial.  These steps are known as the "Scala Sancta," which is Italian for "Holy Stairs."  Today many people kneel and pray at each of the steps. 


330        By this year, Constantine had rebuilt the city of Byzantium and changed its name to Constantinople.


The Big Picture:  The Significance for Christianity (even today) of Constantine's Move

Diocletian (emperor to 305 and died in 313) realized that the Roman Empire was too large for one person to control and so divided the Empire between the rule of two emperors; one controlled the western part of the Empire and one the eastern part.  Constantine felt he was strong enough to rule the entire empire yet moved his capital eastward from Rome to Constantinople; this may have reflected growing concern for the stability of the eastern front of the Empire.  The Empire vacillated between rule by one emperor and two until 394, when Theodosius became the last sole emperor of the entire Empire.  Upon his death, the Empire was divided between Theodosius' two sons.  This divide in the Empire reflected differences between the two halves of the Empire which existed well before 394.  Eventually these differences would help result in Christianity splitting into western and eastern Christianity:  Catholicism in the West and centered in Rome and Orthodoxy in the East and centered in Constantinople.


337        Constantine outlawed crucifixion.  This basically ended the practice of crucifixion. 


337        Constantine died; he was baptized just prior to his death. 


The Big Picture:  Effect of Constantine on Christianity

With Constantine, Christianity saw its first imperial protector.  Because of this, Christianity itself changed in style.  Christians were no longer persecuted during his reign.  More people became Christian, more resources were spent on building churches, Christians--no longer fearing for their lives--spent their effort in developing Christian thought and understanding through education and writing, and the church services themselves developed more elaborate ceremonies, such as clerical dress (vestments) during the service, incense, processionals before and after the worship service, and choirs.


337-350        Rule of the Roman Empire fell to Constantine's three sons, Constantine II, Constans, and Constantinus II.  The different parts of the Roman empire vacillated between Arian and Nicene belief. 


340        Eusebius, Bishop of Caesarea, died.  He is considered the father of Church History.  He wrote the first comprehensive church history work, entitled "Ecclesiastical History" or "Church History," completing the final Book X in 323. 


340        Paul of Thebes, the first known monk, died.


342        Eusebius, Bishop of Nicomedia, died.  He was a leader in the Arian party and baptized Constantine before the emperor died.


346        Pachomius, who established the first monastery and the first Rule (rules for running a monastery), died.  To learn how his first attempt at creating a monastery failed and what he did to restart the operation, go to the year 320.  At his death he ruled over eleven monasteries:  nine for men and two for women.


350        Constantinus II becomes sole emperor of the Roman Empire.  He was Arian; for an explanation, see the year 325.  He ruled until 361.  During his reign, Arian thought spread throughout Christianity.  Jerome wrote, "the entire world woke from a deep slumber and discovered that it had become Arian."


The Big Picture:  Arianism Post-Nicene

One of the main ideas which thwarted people in the first 350 years of Christianity was the idea of the Incarnation, of God becoming human, and the Trinity, one God in three persons, Father, Son, and Holy Spirit..  Many of the early heresies taught different versions of the identity of Jesus.  The cause of this lengthy confusion was the inability to accept that Jesus was God.  Arius believed that Jesus, being called the "Son," was created at some point in the past by the Father.  This idea appealed to many people as well, such that after the Council the Arian view only grew.  A number of church leaders wrote against Arianism, including Anthanasius, Basil the Great, Gregory of Nyssa, Gregory of Nazianzus (there three are known as the Great Cappadocians), and Ambrose.  A second Council, the Council of Constantinople in 381, also attempted to end Arianism, but the heresy remained alive for several hundred years.


354        Augustine is born.


356        Antony, the most popular of the desert monks, died.  He popularized eremitic monasticism (living alone).


360        Martin of Tours and Hilary of Poitiers founded the first monastery in Gaul (present-day France).


362        Julius (who had become emperor the year before) was not a Christian and reopened the pagan temples.  He did not persecuted Christians, though.


363        Julius died.  Jovian became emperor and restored Christianity to its place of prominence in the Roman Empire.  He died in the following year.  All emperors from Jovian were Christian.


364       Basil the Great issued his Rule, which is the basis of Eastern monasticism.  Benedict of Nursia will issue his Rule, which will be the basis for Western monasticism, in the early sixth century.


367        Development of the Canon:  Athanasius, Bishop of Alexandria, writes a letter which includes a listing of the 27 books he believes should be in the new Christian scripture.  This is the first known listing of the New Testament books.  To read the portion of the letter which addresses the 27 books of the New Testament, go here.  To read about the development of the Canon, Creed, and Clergy, go to The Big Picture after the year 117.


380        The Emperor Theodosius I decreed that Christianity would be the official religion of the Roman Empire.  To read the proclamation, click here.  Inherent in this declaration was the concept of the Trinity, therefore a rejection of Arianism.  It is noteworthy that Theodosius did not gain control over the entire Empire until 394, when he defeated the Western Emperor Eugenius.


381        Emperor Theodosius I convened the Council of Constantinople, the second Ecumenical Council.  This was the second of the twenty-one major Church Councils.  This Council was called to refute the ideas of Arius and Apollinarius.  The latter believed that, while humans have a physical body, soul, and spirit, Christ only had a physical body and soul.  The spirit which humans have was in Christ the "Divine Logos."  The Council developed a creed in response to this heresy.  Read the Creed here.  Today this Creed is (usually) known as the Nicene Creed.  In addition, Constantinople was given "honorary precedence" over all churches except for the Roman church. 


382        Theodosius I entered into a peace contract with the Visigoths.  Twenty-eight years later they would defeat and sack Rome.


393        The Synod of Hippo approved the 27 books of the New Testament.


390        Bishop Ambrose forced Theodosius I to publicly repent on his knees because of a massacre which the emperor caused.  This is the first time an emperor--or, in other words, a secular ruler--was forced to be subjected to a church leader.  To learn more about the massacre and repentance, click here.


395        Theodosius I died.  The Roman Empire split into eastern and western parts and never rejoined.


397        The Council of Carthage approved the 27 books of the New Testament.


The Big Picture:  Canon, Creed, and Clergy Established:  The Church Institutionalized

By the end of the Fourth Century, Christianity had a Canon (Scripture of Old and New Testaments), Creed (Nicene) and Clergy (priests, bishops, and "bishop of bishops" which we call the Pope).  This completed the institutionalization of Christianity, that process where Christianity developed its own writing (canon), its declaration (creed) and its leaders (clergy).  In addition, Christianity was the official religion throughout the Roman Empire.  In 395, prior to Theodosius dying, Christianity as a movement was on the rise with few impediments.  But fifteen years later Rome would be sacked and the beginning of the Dark Ages would begin.


Late 300s       John Chrysostom was Bishop in Constantinople.  He is known as one of the greatest preachers in Christianity.  Find out why he was nicknamed "Golden Mouth" here.


Late 300s       The idea of the perpetual virginity of Mary dates from at least this period.  This is known because Jerome wrote against a theologian named Helvidius who did not believe that Mary remained a virgin.


Primary Sources

Nicene Creed of 325

"We believe in one God, the Father Almighty, Maker of all things visible and invisible.

And in One Lord Jesus Christ, the Son of God, begotten of the Father, the only-begotten; that is, of the essence of the Father, God of God, Light of Light, very God of very God, begotten, not made, being of one substance with the Father, by whom all things were made both in heaven and on earth; who for us men, and for our salvation, came down and was incarnate and was made man; he suffered, and the third day he rose again, ascended into heaven; from where he shall come to judge the quick and the dead.

And in the Holy Spirit.

But those who say:  'There was a time when he was not,' and 'He was not before he was made;' and 'He was made out of nothing,' or 'He is of another substance' or 'essence,' or 'The Son of God is created,' or 'changeable,' or 'alterable'--they are condemned by the holy catholic and apostolic Church." 

To go back to the Council of Nicea, click here.


Portion of Athanasius 39th Festal (annual) letter of AD 367 concerning the 27 books of the New Testament:  "These are, the four Gospels, according to Matthew, Mark, Luke, and John.  Afterwards, the Acts of the Apostles and Epistles (called Catholic), seven, viz. of James, one; of Peter, two; of John, three; after these, one of Jude.  In addition, there are fourteen Epistles of Paul, written in this order.  The first, to the Romans; then two to the Corinthians; after these, to the Galatians; next, to the Ephesians; then to the Philippians; then to the Colossians; after these, two to the Thessalonians, and that to the Hebrews; and again, two to Timothy; one to Titus; an lastly, that to Philemon.  And besides, the Revelation of John.

    These are fountains of salvation, that they who thirst may be satisfied with the living words they contain, In these alone is proclaimed the doctrine of godliness.  Let no man add the these, neither let him take ought from these."  To go back to Athanasius, click here.


Proclamation declaring Christianity the official religion of the Roman Empire:  "It is our desire that all the various nations which are subject to our clemency and moderation, should continue to the profession of that religion which was delivered to the Romans by the divine Apostle Peter, as it has been preserved by faithful tradition and which is now professed by the Pontiff Damasus and by Peter, Bishop of Alexandria, a man of apostolic holiness.  According to the apostolic teaching and the doctrine of the Gospel, let us believe the one deity of the Father, the Son and the Holy Spirit, in equal majesty and in a holy Trinity.  We authorize the followers of this law to assume the title of Catholic Christians; but as for the others, since, in our judgment they are foolish madmen, we decree that they shall be branded with the ignominious name of heretics, and shall not presume to give to their conventicles the name of churches.  They will suffer in the first place the chastisement of the divine condemnation and in the second the punishment of our authority which in accordance with the will of Heaven shall decide to inflict."  To go back to Timeline, click here.  Bettenson, p. 22.


The Creed which came out of the Council of Constantinople:

    "We believe in one God, the Father Almighty, Maker of heaven and earth, and of all things visible and invisible.

    And in one Lord Jesus Christ, the only-begotten Son of God, begotten of the Father before all worlds, Light of Light, very (or true) God of very (or true) God, begotten, not made, being of one substance with the Father; by whom all things were made; who for us men, and for our salvation, came down from heaven, and was incarnate by the Holy Ghost of the Virgin Mary, and was made man; he was crucified for us under Pontius Pilate, and suffered, and was buried, and the third day he rose again, according to the Scriptures, and ascended into heaven, and sits on the right hand of the Father; from where he shall come again, with glory, to judge the quick (living) and the dead; whose kingdom shall have no end.

    And in the Holy Ghost, the Lord and Giver of life, who proceeds from the Father, who with the Father and the Son together is worshiped and glorified, who spake by the prophets. 

    In one holy catholic and apostolic Church; we acknowledge one baptism for the remission of sins; we look for the resurrection of the dead, and the life of the world to come.  Amen."  To go back to the Council of Constantinople, click here.

Question/comments contact Mark at


Bainton, Roland.  Early Christianity.  Second Edition, 1984.  ISBN:  089874735X.

Cross, Frank L., ed.  The Oxford Dictionary of the Christian Church.  Second Edition, 1993.  ISBN:  0192115456.

Source for clerical celibacy quote: and see Canon 33.