We know very little about the first "Christians" - followers of Joshua (or Jesus "the Messaiah/Christ" as he was called by the Greeks). From purely historical perspective we know nothing at all. Religious texts written 100 years after the events are hardly reliable sources of historical information. Basing your history of early Christians on the New Testament is a bit like relying on Das Kapital and Mein Kampf for representation of events in the 19th/20th century.
Based on what we do know it appears that there were two separate groups of early "Christians" - one in Judea and the other in the Jewish Diaspora in the Roman Empire. For a while they were indistinguishable from other Jewish sects.
In those times Judeans were persecuted by the Romans as citizens of "the most insubordinate of all the provinces". They refused to worship the deified Emperors and constantly revolted against he legions. It did not help the situation that there was continuous infighting between different Jewish groups, corruption at the top, even terrorism. Romans used to Crucify Jews in their thousands on a regular basis until, eventually, they flooded Palestine with blood, expelled the Jews and renamed Jerusalem. At that time Jews generated a whole bunch of "Messiahas". The same phenomenon could be observed again during the most difficult times in the Middle Ages when people had no other hope.
At first "Christians" were subjected to exactly the same treatment as the other Jews. It was at that time that a fraction of this Jewish sect decided to step away from Judaism and commenced missionary activities among non-Jews. In order to achieve their purpose they removed those aspects of Judaism which were hard for non-Jews to accept (e.g. circumcision). To make conversion more attractive other religious practices and beliefs were borrowed from the people in the Empire. For example in this manner Christianity developed the concept of Resurrection (Zoroastrianism) and the cult of Mother-Goddess (Anatolia).
Judean uprisings, such as that of Bar Kokhba (132-136 AD) were not supported by the early Christians. This lead to a deterioration of relationship between the new religion and the Jews but served the objective of improving relationship with the Romans.
It was at this time (between 117 and 138 AD) that the New Testament was written, partly on the basis of earlier texts. It was this era, its purposes, propaganda and relationships that are preserved in the Gospels according to which Jews are "a brood of vipers and children of the devil".
This text caused medieval antisemitism. In the last couple of centuries Christianity developed and largely managed to rid itself of the disease but the ancient prejudices migrated into Islam and other political/religious movements including communism, nazism, neo-nazism and certain sections of the "progressive" community.