Our earliest knowledge of the beginnings of Christianity in Europe is, of course, from the New Testament and, in particular, from the Letters of St. Paul and the Acts of the Apostles.   The fact that he was both a Jew  and a Roman citizen enhanced his work of missionary zeal for Jesus Christ.   Clearly he had established modest congregations in Asia Minor and what is now Syria and Turkey but with his Missionary Journeys he was able to aid in the spreading of the Gospel to what is now Greece in Corinth, Athens, Thessalonica, Macedonia, Malta and as far as Rome.    Clearly he worked with others including Barnabas, John Mark, Apollos, Timothy and  Luke who wrote both the Gospel of that name and the Acts of the Apostles from which we learn so much, together with the letters of St. Paul, of the earliest church following Our Lord`s Ascension.
The time was ripe for the spread of the Christian Gospel and not least because of the improved communications available through the Roman Empire.   However, during the fir four centuries of the Christian Mission there was much  persecution and , notably, under the emperors Nero, Domition, Decius and Diocletian.    It was only under the enlightened reign of Constantine that Christianity was recognised and respected as a religion in the Empire.   Indeed Constantine, who was likely baptised on his death-bed, was the son of Helen, a Christian British woman which points to the fact that there must have been groups of Christians in Britain as early as the fourth century.
From the time of Constantine the Great Christianity began to spread through Europe both East and West but it was anything but a monolithic structure and though the tenets of Our Lord`s teaching were common the local expressions and traditions had considerable variety.    The supremacy of the See of Rome was established fairly early on with Constantinople being established the Emperor as the second most important See in Europe.
The establishment of monastic communities took place under Celtic influence but even more importantly under the influence of St. Benedict whose monastic rule, noted for its moderation was based on the three foundations of OBEDIENCE, STABILITY and CONVERSION OF LIFE.   He had, of course, been influenced by the teachings of St. Antony of Egypt but who had been born and brought up in Como, Italy.   Benedict was also influenced by the life of St. Basil the Great who was the elder brother of St. Gregory of Nyssa and the friend of St. Gregory Nazianzus with whom he studied in Athens.   So we see that the early church had both, as today, a local and an international context.
The Benedictine communities, established first in Italy, began to grow and spread through many parts of Europe and as well as leading the monastic and community life also became involved in Christian education with many monasteries having schools attached to them.   Benedict lived from AD 480 to about AD 550.    One of the fairly immediate followers of St. Benedict was St. Gregory the Great, born in 540, was a monk ordained deacon by Pope Benedict I who was later elected as Pope himself and had tremendous administrative gifts and missionary zeal and who not only established the supremacy of the See of Rome but placed the Church in Spain under the care of his friend Bishop Leander.   It was he, too, who resolved to re-invigorate the Church in Britain by sending Augustine, formerly Prior of St. Andrew`s Abbey in Rome, with companions  Paulinus (of York) and  Mellitus.  Augustine became Archbishop of Canterbury and enjoyed the protection of Queen Bertha and converted her husband King Ethelbert of Kent, Paulinus established the See of York as well as being chaplain to the already Christian Queen Ethelburga of Northumbria and baptised her husband King Edwin .   After five years he returned south and became first Bishop of Rochester and Mellitus became Bishop of London and there was considerable consolidation of the Christian Church.   There had, of course, been a Celtic presence in the British Isles.   Indeed there was much coming and going of Christian missionaries throughout Europe with Armenia having an established church as early as AD 301 under King Trdat III.   The Apostle Bartholomew together with Judas Thaddeus are said to have brought the Gospel of Jesus to that  eastern outpost of Europe.   St. Irenaeus records the persecution of Christians around Lyons in France in AD177 so there is clear evidence of a growing church in that part of France and St. Hilary was consecrated as Bp. Of Poitiers in AD 353.
Christianity flourished in what is now Germany from 800 under the Emperor Charlemagne though the Devonian, St. Boniface, had spread the Gospel to Friesland becoming Archbishop of Mainz in 732 having established a number of monasteries and dioceses.   Indeed, it has been said that `…nole Englishman has had a deeper influence on the history of Europe than St. Boniface.`
Forgive me if this sounds a bit like a travelogue or Cook`s Tour of Christian Europe but the spread of Christian Teaching has been rather like that.
Central and Eastern Europe initially came under the influence of Orthodox Christians from the  Patriarchate of Constantinople including SS. Cyril and Methodius who brought the Gospel to what is now Hungary and the Czech Republic though both these lands fell soon after under western rather than eastern influence.   This was in the 9th century.   The two brothers, one a bishop and both monks became known as the Apostles of the Slavs.   Their influence spread not least because of the development of the glagolithic and Cyrillic alphabets and the liturgical language of Church Slavonic.   In the Ukraine Christianity was established as the national religion by St. Volodomyr the Great, Ruler of the Kievan Rus,  in 988 importing the Orthodox form of Christianity from Constantinople.    From the Kievean Rus  Russia also received the Gospel.
There are records of early Christianity in the Iberian Peninsula and there is the tradition that St. James brought Christianity to Galicia and certainly a bishopric had been established in Braga, North Portugal by the end of the fourth century.
I suppose that Scandinavia was the last part of Europe to receive the Christian Gospel and tyhis took place between the 9th and 12th centuries though parts were not converted until the early 19th C.
The Church, being a school for sinners, has always been much less than perfect and abuses and power-politics have been seen to abound over the centuries leading to the Great Schism between the Catholic and Orthodox Churches, centred on Rome and Byzantium respectively, taking place in AD1054 leading to mutual excommunication.
The Orthodox East really consists of a Family of Autocephalous Churches yet not always respecting each other.
In the West there spring up a growth of Religious Orders – some monastic living the Benedictine Mixed Life of Stability, Obedience and Conversion of Life but embracing the life of Worship and prayer at its heart but tempered with physical labour too as well as study and some stricter reformed versions of this both for men and women, others were mendicant such as the Franciscans, founded after the manner of St. Francis of Assisi – an Italian who went about preaching and missionising, (St. Francs lived from 1181 – 1226), and The Dominicans after the method of St. Dominic – a Spaniard who lived from 1170 to 1221.   There were also Carmelites among whom were St. Teresa of Avila (1515 – 1582) and St. John of the Cross (1542 – 1591) both Spanish Mystics and Reformers but within the Catholic church.
The Church of the West likewise has become very fractured with the split between Catholics and Protestants taking place from the time of  Martin Luther and John Calvin.  Luther had wanted to reform the church from within whereas Calvin wanted a much stricter reform and a full break-away from Catholicism.   The historical reality has been the breakdown of the Western Churches into many separate denominations -  a large number of whom had abandoned the three-fold ministry of Bishop, Priest and Deacon for a ministry of Ministers and Elders.    Main, and very different, leaders of the Protestant Reformation were John Hus (1372 – 1415), Martin Luther (1483 – 1546) and John Calvin (1506 – 1564).
Here in England Henry VIII following his excommunication declared himself supreme Governor of the Church of England and, over a period broke away from Rome and an independent church was established – and more fully by the reign of Elizabeth I but holding to the 3-fold ministry fouind in the older and traditional churches of both East and West and yet more fracturing of the Western Church, in particular, as the years moved on:
Anabaptists and Baptists in a number of varieties, Methodists in a number of varieties, Presbyterians in a number of varieties, Congregationalists, Pentecostalists and so on reaching many hundreds of independent congregations or gathering so those professing to be Christians.
Our Lord Jesus Christ, recognized divisions among his own followers and, as we know, prayed that the Church might be One.   We too must strive for and pray for the Unity of Christ`s Church recognizing that such division is a scandal but also recognizing that we must seek the Truth.