There is no doubt that Christianity evolved out of Judaism and that Jesus was a Jew. In the years following his death, there were many sects of Christ's followers who harkened to elements of his teaching and attempted to follow his advice.

These groups of followers of Christ which eventually became known as Christians remained a thorn in the side of the establishment, but they soon spread despite a great deal of persecution.

Jesus had shared some great teachings providing new values for a peaceful and purposeful life which the authorities appreciated, after all at the time there were a great many gods which differed between regions of the empire.

The persecutions ended for a short time after Roman Emperor Constantine the Great converted to Christianity following his victory at the Battle of Milvian Bridge in 312 and he made Christianity the state religion in order to consolidate power over the empire.

It is debated whether or not Constantine was actually a believer (according to his confessions and understanding of the faith) or just someone trying to use the church and the faith to his own advantage.

Constantine called the first general council of the Christian church in Nicea Turkey in 325 A.D. and it was here that the 318 learned Christian referred to as bishops decided the shape of Christianity which was the beginning of the Catholic Church or church of Rome.

The most important point to note here is that the church was to now be the intermediary between God and the people,  as well as the interpreter of the will and word of God. Now only the priests and agents of the church could legitimately communicate directly with God and for the people to access God and have their prayers heard and answered, they had to pay the priest.

In the year 367 the books of the New Testament we arranged in exactly the number and order in which we presently have them by Athanasius, Bishop of Alexandria.

Creating History
There is continuing debate and some consensus that the books containing the worlds history and thought and in particular the Zoroastrian religion served as a model on which to build the modern Christianity and that the instigators of modern Christianity made good use of the great libraries of Alexandria to study the past and formulate the new religion.

The prominent historic view attempts to discount this theory however researchers have established that it is highly unlikely that the great libraries of Alexandria were burned in 48 BC as claimed.

It is far more likely that the Christian Patriarch Theophilus of Alexandria destroyed the books if not the libraries themselves in 391 on the orders of Emperor Theodosius who certainly wanted the rid the world of pagan ideas and very likely also wanted to eliminate the details surrounding the formulation of the new Christianity and any remaining books were likely destroyed after the Muslim conquest in AD 642.

Second Council of Nicea and the Seventh Ecumenical Council. It concluded that icons were worthy of veneration but not worship, and restored their use. 

Christianity was now well established and spreading and the only word of God was that sanctioned by the Catholic church and although emperors rose and fell, and even Christians were persecuted under different rulers, Christianity spread under the power and influence of Rome.

The biggest threat to the new religion came with the advent of Islam which soon after its inception, soon spread into Eastern Europe, North Africa and Southern Spain. Islamic rule is reported as more tolerant than Christian rule and did not require conversion to Islam, however these faiths have fallen into great competition for lands and people.

The Catholic church remained dominant throughout the Roman empire and after its demise as the armies of Rome fell back from the provinces of Europe Christianity remained.

The church was rich and powerful owning a large portion of the now Italian Peninsula, (the papal States). As the accepted intermediary between God and the people, the church must have seemed invincible. It made a huge fortune from its services which largely consisted of ecclesiastic malpractice, the teaching and the sale of indulgences, and simony, the selling and buying of clerical offices.

Martin Luther
Martin's criticism of the church made him an enemy of the church although he was simply stating the obvious. He saw fist hand how corrupt the church was, particularly the administration; the pope and hierarchy who were into every kind of debauchery. Martin Luther describes the licentiousness of a party he attended where after the main meal, wine and drunkenness, a large cake was bought in from which emerged about 20 naked boys for the pleasure of all gathered.

In pointing out the obvious, Marin Luther was hailed as a hero and this began the reformation and a division within Christianity resulting in Protestantism and the pantheon of Christian sects we see today.

The Catholic church however fought back with the persecution of non Catholics know as the inquisition which was to last for hundreds of years and claim the lives of many thousands of not only those the church inquisitor considered pagan, but even those considered not very good Catholics.

Final Reformation
The papal States were ruled by popes from 754 until 1870. These were originally given to the papacy by Pepin the Short and reached their greatest extent in 1859, however the emperor Napoleon ended this tenure and the church retreated to the Vatican , the last papal state which was formally established as a separate state by the Lateran Treaty of 1929.

Since then the divisions of the Christian church have charted independent courses with different interpretations of the bible and Christian history and providing services to the people and governments to justify their existence.

With the rise of democracy, the people now have greater freedom to compare religions and systems of belief and the church is perhaps reaping its own karma as atheism grows and the differences of faith are still the cause of most of the worlds conflict.

Reference books

References
http://www.gotquestions.org/constantine-bible.html
http://en.wikipedia.org/wiki/Library_of_Alexandria
http://www.davidmacd.com/catholic/timeline_of_catholic_church.htm