I.  Starting with Pentecost, the Church expanded rapidly throughout the Roman Empire.  Acts of the Apostles describes some central events in the early expansion of the Church.

A.  At Pentecost, the Holy Spirit came upon the early Christians and, from that time onward guided them to spread the Gospel throughout the known world.        

1.  At the Last Supper, and again before ascending into heaven, Jesus promised the Apostles that He would send the Holy Spirit to them, and that they would be witnesses of the Gospel to the far ends of the earth.  John 14:15-17, 15:26-27, 16:7-15; Acts 1:8.

2.  Ten days after the Ascension, on the fiftieth day of the Resurrection, which was during the Jewish feast of Pentecost, the Holy Spirit came to Mary, the Apostles, and the early Christian community gathered in Jerusalem (about 110 total) in the form of a colossal wind and flames of fire.  The early Christians then proclaimed the Gospel in Jerusalem, and brought in 5000 converts that day.  Acts 2:1-36.

B.  Soon Christianity expanded throughout the Jewish and Samaritan communities, and then throughout the Roman Empire.  

1.  Acts of the Apostles records both the opposition of the leaders in Jerusalem to the new faith and the rapid expansion of the number of Christians in the Church, which enjoyed mostly internal peace in the face of external opposition.  See, e.g., Acts 4.  With the expansion of the Church, the Apostles appointed the first new clerics, seven deacons, to help with administration.  See Acts 6:1-7.  Among the earliest martyrs was one of those deacons, St. Stephen, who was stoned to death when he criticized the negativity of Jerusalem.  Saul (soon to be called Paul) presided at the stoning.  See Acts 7.

3.  Soon the Gospel spread to Samaria and Syria; and even the Apostles were astonished at the fact that the grace of God was coming to pagan nations.  See Acts 8-14.

4.  In the midst of this spread of the Gospel, the leaders in Jerusalem sent Saul to arrest Christians in Damascus, the capital of Syria.  While Saul was on the way, Jesus appeared to him, and brought him to faith in Him.  In Damascus, Saul would learn about the faith from Annanias.  Soon, the Holy Spirit would guide the Apostles to commission Saul (now called Paul), along with Barnabas, to begin missionary work in the Church, first in Syria and then to other nations.  See Acts 9:1-30, 13:1-14:28.

5.  With new converts coming in from pagan nations, the issue arose of whether those converts had to adhere to the Jewish ritual laws.  At the Council of Jerusalem, St. Peter led the Apostles and the whole Church to decide that the new converts did not have to adhere to the Jewish ritual law, although there were some requirements to avoid unnecessary offense.  See Acts 15.

D.  Most of the rest of Acts of the Apostles describes the missions of St. Paul to bring the Gospel to Asia Minor (modern day Turkey), Macedonia, Greece and the Aegean peninsula generally.

E.  For different reasons, St. Peter and then St. Paul ended up in Rome, where Acts of the Apostles ends.  They were both martyred there, and thus consecrated that city as the new capital of the Church.

F.  Other Apostles and early Christians also evangelized far off lands.  Thus, according to ancient traditions, St. James the elder brought the Gospel to Spain and St. Thomas brought the Gospel all the way to northern India.  The people who had converted to Christianity at Pentecost also came from many nations, and presumably brought the message back to those lands as well.

G.  As the first witnesses to Jesus were beginning to die off, the evangelists began writing accounts of the life of Christ, based largely upon the preaching the Apostles and others who had been witnesses to His life.  The Scriptural Gospels of Matthew, Mark, Luke and John were all from the first century and had an apostolic origin, being written by either the Apostles themselves or (as with Mark and Luke) by their assistants.  See Vatican II Council, Dei Verbum 19 (1965.)

H.  The epistles of the New Testament come largely from communications with these communities.  They likewise have an apostolic origin, being written either by the Apostles (including St. Paul) or by their assistants.

1.  St. Paul wrote numerous letters to the communities that he had evangelized.  The fourteen Pauline letters in the New Testament were mostly written to communities that St. Paul evangelized or, as with 1 and 2 Timothy and Titus, to bishops he commissioned.  The Letter to the Hebrews was written to formerly Jewish Christians to demonstrate that Christianity was not an abandonment of their traditions but a fulfillment.  Philemon was likewise written to a prominent early Christian.

2.  St. Peter, St. John, St. James and St. Jude, or their disciples, also wrote letters to the early Christians reflecting upon different aspects of the faith.  They are often called the “catholic letters” because the Greek word catalicos means “universal”; and these letters were not written to any specific communities, but more for general circulation.

I.  St Luke wrote the Acts of the Apostles to record some of the history of the early Church, particularly emphasizing its unity in the face of opposition, and the spread of the Gospel to all the world.  The book begins in Jerusalem and ends in Rome, the new capital of the Church.  The Book of Revelation presents in symbolic form the victory of God’s kingdom in the face of all opposition during the first century, and by extension throughout human history.

II.  Meanwhile, secular opposition to the Christian faith also increased, starting in Jerusalem, spreading to pagan lands, and finally reaching the imperial throne itself.

A.  Early on, the tetrarch Herod began persecuting the Church, more for popularity than for any beliefs of his own.  He beheaded St. James the elder, the first Apostle to be martyred, and then launched a general persecution in Jerusalem and the surrounding areas.  See Acts 12.

B.  Acts of the Apostles also records opposition rising to St. Paul’s proclamation of the Gospel, sometimes because of the economic interests of the pagan temples.  See, e.g., Act 19:23-27.

C.  At first, the Roman Empire’s imperial government did not seem to take much interest.  Acts of the Apostles records the Roman officials and local kings such as the governor Festus and the king Agrippa puzzled by the controversies.  See Acts 25.

D.  However, the Roman Emperor Nero, in order to deflect unpopularity from himself, which especially increased after allegations that he set the great fire of Rome in 64, began persecuting Christians.  He was overthrown by the Senate and committed suicide in 68, but the persecutions continued to varying degrees.  The persecutions were worst in Rome, where the Circus Maximus and the Colosseum were places of torture and death, generally with the crowds looking on for amusement.

E.  We have records from many of the early martyrs, such as those of Polycarp and Perpetua and Felicity.  Also, many Christians who were persecuted wrote texts that are helpful in understanding Christianity today, such as the works of St. Justin the Martyr and the letters of St. Ignatius of Antioch, both from the mid-2nd century.  

F.  There were also Romans who wrote about Christians.  For example, Pliny the Younger, the Roman governor to what is now Spain, wrote a letter to the Emperor Trajan about the year 112 asking him how to deal with Christians.  Trajan maintained that the governor must stop Christianity, but put limits on how this opposition was to be carried out.  Some other Roman commentators, such as Celsus in the second century and Porphery in the third, wrote in opposition to Christianity.  

-  Meanwhile, Christians such as St. Justin the Martyr, St. Ireneus, Origin and St. Cyril of Alexandria wrote defenses of the faith, doctrinal works and Scriptural commentaries that are widely used to this day.

G.  The persecutions became much worse in the 250s under the Emperors Decius and then Valerian who believed that they could revive paganism by increasing the persecution of Christians.  

1.  The Emperor Decius tried to restore piety and discipline to the Roman Empire and thought that suppressing Christianity was a part of his program.  And so, in 249, he issued a decree mandating that all people make offerings to the Roman gods.  He was killed, however, in 250 when fighting the Goths in what is now Germany.

2.  His successor Valerian once again ordered a persecution again in 252, especially aimed at the Christian clergy.  However, the Persians captured him in battle in 257.

3.  His successor Gallienus rescinded both orders, and there was peace for a time.  

H.  However, under the influence of his advisor, and later sub-emperor (called Caesar) Galerius, the Emperor Diocletian launched the most vicious persecution of the Christians ever in 303.   That persecution lasted until the year 311 when Celsius, now Emperor in the East, called it off under great pressure.

-  Diocletian became Emperor at a time of great political, economic and foreign policy crisis, as the imperial government was becoming more inefficient, trade and transportation were declining, and foreign powers from the Germanic tribes of the north and the Persian Empire from the east were pressing against the frontiers.  He did stabilize the situation, and improved government and military discipline.  To make governance easier, he also divided the Empire in two, east and west, or Greek and Latin speaking areas, each with its own Emperor. But in his later years, he became paranoid about Christians and launched the terrible persecution.

III.  As the early Church grew, she would gradually develop her early practices and teachings, often in the fact of struggles and heresies.  

A.  The Scriptures themselves give an indication of early practices of the Church, including the ordination of bishops (episcopoi), priests (presbytoi) and deacons (diaconoi) as described in 1 Timothy and Titus, and the Eucharist (along with some problems of laxity) as described in 1 Corinthians.

B.  There were also other non-canonical Gospels written by those who wished to give an account of Jesus.  Some of them, such as the Protoevangelium of James and the Gospel of Peter, while not written by the Apostles, still give mostly reliable information about Jesus and the Holy Family.  Other attempts at gospels, such as the so-called Gospel of Thomas, the Gospel of Judas, and the Gospel of Mary Magdalene, have very erroneous theology.

C.  Some other writings, such as a letter from Pope St. Clement of Rome to the church in Corinth, the Didache and the Shepherd of Hermas give a picture of the early Church.  While not canonical, their insights often provide a sense of the first springtime of the Church.

1.  The letter of Pope St. Clement to the Corinthians dates from about 96, and describes the importance of clergy and unity in the Church.

2.  The Didache (the Teaching of the Twelve Apostles), probably written in the early first century, deals with morals and some matters of Church governance, such as how to respond to new preachers and how to administer baptism and the Eucharist.

3.  The Shepherd of Hermas, written by a unknown author in the first century, describes visions, moral law, and parables designed to guide the Christian life and to bring about repentance.

D.  The accounts of the martyrs and the writings of those who defended Christianity also give us an insight into the practices and understanding of the early Church.

1.  For example, the letters written by St. Ignatius, bishop of Antioch, to various churches while on his way to martyrdom in Rome in the mid-second century, emphasize the nobility of sacrifice, and the need for a unified, moral Church.

2.  St. Justin the Martyr (d. 165) wrote his First Apologia to the Emperor Antoninus and the Senate and people of Rome, patiently explaining the faith as bringing out the best in Roman culture and the fulfillment of the virtues sought by the philosophers.  He also wrote Second Apologia to round out the teachings, and the Dialogue with Trypho to argue that Christianity fulfilled the Jewish faith.  His writings give us an early description of such practices as the essential elements of the Mass, and the importance of morals in the early Church.

3.  The account of the martyrdom of Saints Perpetua and Felicity (circa 203) indicate, among other things, the importance of prayers for the dead.

E.  Throughout all of this time, the early practices of the Church were gradually developing.

1.  As the Vatican II Council explained, the universal early practices of the Church, such as the veneration of Mary, the structure of the Mass, the roles of the clergy, and the books recognized as Scripture form the Sacred Tradition of the Church which stands alongside of the Bible as a part of Revelation.  See Dei Verbum 8-9.

2.  Thus, for example, the letters of St. Ignatius and the account of the Martyrdom of St. Polycarp (about 100) describe early roles of the bishops, priests and deacons.  See, e.g., Didache ch. 15; Letter of St. Polycarp to the Philadelphians ch. 5-6; Letters of St. Ignatius of Antioch to the Trallians ch.3 and to the Magnesians ch. 3-4, 13, and to the Philadelphians ch. 7-8.

3.  Likewise, the early Christians venerated the saints and celebrated Masses at their tombs, as is indicated by the excavations of the catacombs around Rome.  The Christians did not hide out in the catacombs, for they were not the mazes we see now, but rather rooms for burials.  However, the altars and symbols at the catacombs indicate a strong belief in the intercessions for and from the dead.

        F.  Early on, the Church had to deal with Gnosticism and related heresies.

1.  Gnosticism was a Greek based philosophy, but it found its way into Christianity.  Gnosticism taught that our souls were created in an entirely spiritual realm, but are now trapped in this world by demiurges, or powerful beings that fell from the greater realm and made this one.  The gpa; is to get back to that greater realm through a sort of secret knowledge.

2.  Such erroneous writings as the Gospel of Thomas present Jesus as one who would, by this secret knowledge, free us to leave this earthly body.  There were variations of attempts at Christian Gnosticism, but they all maintained that Jesus did not really become man, but only appeared to do so.  St. John’s letters indicate that this error was a problem early on.  See 1 John 4:2-3; 2 John 7.

3.  One version of Gnosticism in Christianity was proposed by Marcion in the second century.  He argued that the Old Testament was inspired by a lesser, or perhaps even evil, god, who emphasized justice, but not mercy and grace, and who was violent and focused on things of this world.  He accepted only part of the New Testament, including the Gospel of Luke and the letter to the Galatians, as truly the inspired word of God.

        G.  Another group that broke from the Church was the Montanists.  

1.  About the year 170, a charismatic preacher named Montanus preached a particularly severe brand of Christianity.  Among other things, it denounced property and marriage as evils and said that sinners who fell away from the faith could not return.

2.  About the year 200, Tertullian, who had been a Christian theologian, took up the cause of Montanism and eventually rejected secular philosophy as worthless and the clergy as unnecessary.

H.  At times, antipopes claimed to be the rightful leaders of the Church for the sake of championing some erroneous cause.  The most famous of them was Hippolytus, a theologian for the Church who then claimed to be Pope in 212, arguing that Popes Callistus and then Sixtus were too lenient towards sinners.  When the Roman government exiled him and Pope Pontian (230-35) to exile in Sardinia, they reconciled.  Pope Pontian resigned the papacy and both of them accepted his successor Pope Fabian in 236.

I.  Many great Christian theologians (called apologists after the Greek word for explanation) responded to the heresies by emphasizing the true faith.

1.  Thus, St, Irenaeus, bishop of Lyons (178-202), wrote expositions of the true faith wrote many works explaining the faith, including Against Heresies, in which he refuted Gnosticism and emphasizes the importance of tracing the true faith back to the Apostles.

2.  Origin (185-232) wrote extensively about the Scriptures and how to understand them.  He emphasized the spiritual meanings behind the literal words and the moral lessons from the Bible.  Due to disputes with his bishop and some of his views that were later considered heretical (e.g., the pre-existence of souls), he is not called a saint.  However, he was faithful to the Church and her teachings as understood in his day; and his theological insights are still considered valuable.

J.  The Church also had to respond to persecutions and the issue of how to deal with people who had lapsed from the faith or otherwise committed grave sins.

1.  The issue of reconciling grave sinners was a general one, as St. Paul’s letters to the Corinthians indicates.  See 1 Cor. 5:1-5; 2 Cor. 2:1-12.  In the ancient Church, the three gravest sins were murder, adultery and apostasy.  Related sins, such as aggravated injury and fornication were also considered very grave.

2.  However, the question of how reconciliation could come about became more prominent when Christians fell away from the faith during persecutions.

a.  When a persecution broke out, it was considered acceptable to flee to another place to escape it.  In fact, the desert monastic communities were located there partially to escape the Roman government.  It was also considered acceptable to keep a low profile in order to avoid being denounced as a Christian.

b.  However, renouncing the faith or sacrificing to a pagan god was considered to be the equivalent of high treason against the Church.  Likewise, pretending to sacrifice to a pagan god was also considered to be scandalous and gravely sinful, even if one did not actually offer such a sacrifice.

3.  After the persecution of Decius ended with his death in 250, the issue came to the forefront.

a.  Some people, especially called the Novatians, said that people who lapsed from the faith could not come back into the Church.

b.  Other Christian groups seemed to think that people who had lapsed could make a confession to anyone who suffered greatly from the persecution.  Such people who suffered greatly, but had not been martyred, were often called confessors.

c.  The solution, promoted especially by Pope St. Cornelius (251-253)and Saint Cyprian of Carthage (d. 254), was that people who had lapsed from the faith (and by extension all grave sinners) could come back to the Church, but only by going to confession to the bishop or a priest to whom the bishop had specifically given this authority to absolve people of grave sins.  St. Cyprian’s great work The Lapsed, described the idea behind this resolution and the lengthy penances that were needed for restoration.

K.  Both the persecutions and the doctrinal disputes emphasized the need for a united Church.   That need would also come to the forefront when Christianity became legal, and much more popular, after Constantine rose to imperial power in 312.