‘Christianity’ is the collective term used to refer to a large number of faith traditions (churches, sects, denominations) that, in spite of their different doctrines and organisational structures, invoke Jesus Christ as their point of reference and founder. Taken together, Christianity comprises some 2 billion believers today.
To be precise, the history of Christianity does not begin until after the death of Jesus in the year 30 or 33 CE, when Jewish disciples of Jesus proclaimed that Jesus, who, under the Roman governor Pontius Pilate (in office 26‑36 CE) and at the instigation of Jewish circles in Jerusalem, had been sentenced and died on the cross (gallows), had been resurrected, was alive, and that he was the Messiah for which Judaism had been waiting, who would come at the end of time to judge between the living and the dead. Jesus’ followers believed so firmly in this that they proclaimed this message throughout the Roman Empire, and, if necessary, even died as martyrs in the process.
The message quickly found adherents among Jews throughout the Roman Empire. They were soon joined by non-Jews, known as Gentiles, who sought to be admitted to the community of believers who believed in Jesus as the Messiah. An open dispute arose among Jesus’ closest followers (the Apostles) over the question as to whether these followers of the teachings of Jesus Christ (i.e., the Messiah) who had converted from paganism would have to be circumcised and observe Jewish dietary laws. At a gathering of these confidants, known as the Council of Jerusalem, (approx. 50 CE), Paul managed to achieve the decision that the Gentile Christians did not have to be circumcised and were exempt from application of the Jewish dietary laws. This marked the first step toward the breaking away of the Jesus movement from Judaism. Further steps were to follow, after the destruction of the Temple in Jerusalem by the Romans in 70 CE. This resulted in a kind of dividing-up of the inheritance of the religion of ancient Israel into Judaism and Christianity: Judaism evolved into a purely lay religion without a temple cult or priesthood, became ethnically Semitic with the Hebrew Bible as Holy Scripture, turned less to philosophy than to orthopraxy, and ceased proselytizing; Christianity continued the ritual tradition of ancient Israel under a hierarchically organised priesthood, used Koine Greek as its language of worship, read the Jewish Bible in the Greek translation of the Septuagint, integrated Greek philosophy (including its Jewish representative Philo of Alexandria (approx. 20/10 BCE‑40/50 CE), a contemporary of Jesus), and proselytized. Christians abstained from further participation in worship services in the synagogue, and Christianity became a world religion in its own right.
Interpretations of Jesus’ life and teachings led to a fixed canon of guiding scriptures that were combined to create the New Testament; this, together with the Septuagint (i.e., the Old Testament), would henceforth constitute the Christian Bible. The multiplicity of interpretations of Jesus led to contradictory messages, and clarification was needed. Emperor Constantine (in office 306-337 CE), who permitted the religion of Christianity in the Roman Empire, convened a gathering of all of the bishops to resolve the matter. Some (Athanasius [295-373] and his supporters) believed that Jesus was on equal to God; others (Arius [260-336] and his supporters) said that while Jesus ranked at the top of Creation, he was not of the same rank as God. Athanasius’ line of thinking prevailed, and Arius was condemned as a heretic. Consequently, in the years that followed, there was a grave schism within Christianity: on the one side stood the majority of the participants in the assembly of the Council of Nicaea (325 CE), and on the other the opponents who were followers of Arius. In the period following, the latter formed the various Christian churches of the East (e.g. the Armenian, Syrian, Chaldean and Coptic Churches); the views of the adherents within the Empire evolved into a Trinitarian understanding of God (Father, Son, Holy Spirit) that recognised Jesus as true man and true God (i.e. Son). For a variety of political, social and religious reasons, tensions soon developed among the faithful within the Empire. As a result, mainstream Christianity in Europe was divided into an Orthodox East with national churches under the leadership of patriarchs, and a Latin West under the leadership of the Bishop of Rome, the Pope. The final break-up occurred in 1054, some five centuries after the first major schism between the churches of the Roman Empire and of the East. Another five centuries later, there were internal disputes within the Latin Church, due not least to an ever-increasing claim to leadership on the part of the Pope in Rome. The consequence was a schism that gave rise to a heavily Germanic, Protestant Christianity, on the one hand, and the Roman Catholic Church on the other. Many see in this third, great schism the dawn of the modern era: in Protestantism, a hierarchically organised priesthood with the Pope at the pinnacle was now replaced by more protodemocratic forms of organisation that emphasised the general priesthood of all the faithful and rejected hierarchies among the holy orders in general.
The dawn of the modern era can also be seen in the approach taken to science and in scientific investigation into the Bible and the history of Christianity. Even in Protestantism, both led to internal disputes that were expressed most visibly in the conflict between fundamentalists and liberals. The Roman Catholic Church has not been immune to developments of this nature, either. Examples of this are the dispute over modernism at the outset of the 20th century, the Second Vatican Council (1962-1965) and the approach taken to this under Popes Paul VI (1963-78), John Paul II (1978-2005) and Benedict XVI (2005-2013).
No religion is spared the task of grappling with the questions raised by the modern era. The dispute is particularly hard within Christianity, as it sets the tone in, and hails primarily from, those countries that are at the leading edge of the waves of modernisation. The debates concern approaches to the findings of modern science (e.g. heliocentric versus geocentric view of the world, evolution in the field of biology); psychology (e.g. Sigmund Freud [1856-1939]); ethics (e.g. sexuality, gene technology, ecology); and social order (e.g. gender equality, placing homosexual partnerships on the same level with heterosexual marriages as a matter of law).
It is difficult to predict how Christianity will continue to develop in future. There are signs of decline but also signs of an upswing. A glance at history shows that while entire communities of Christians have died out, new communities have emerged as well. The same can be said of controversial positions: clinging to the old order has proven a guarantor of survival in some cases; in other cases it has also stood in the way of survival. So the future is still undetermined. No decision we make today will be without consequence for the future; for the most part, though, any determination as to whether a decision taken is worthwhile or not can be made only after the fact.