Jesus (who
really did exist https://en.wikipedia.org/wiki/Historicity_of_Jesus) started preaching inclusivity, peace, love and understanding
in Palestine, and picked up a few followers. His teachings upset the religious
authorities because it undermined their power, so they conspired to have him
killed.
About 50
years later Saul ("Paul") picked up the stories of Jesus and adapted
it into a religion, largely by putting all the threats and punishments back in,
borrowed from traditional Judaism. He
called it "Christianity".
Missionaries
spread this "Christianity" thing far and wide, but each telling a
slightly different, and in many cases contradictory version of the story, so in
AD340 the Council of Nicea got together and “standardised” it, cutting out the
bits they did not like.
The Council of
Nicea produced a Bible, but they wrote it in Latin so that ordinary people
could not read it, thus enshrining the power of the Church to “interpret” it.
Seeking to
strengthen its power base and finances the Church invented lots of new twiddles
not mentioned in the Bible (but as only they could read it, it didn’t matter) –
e.g. “Purgatory”, where you go after death until a relative still alive pays
the church to release you, and “Papal indulgences”, where you pay in advance
before committing a sin – which succeeded in making it one of the largest and
richest non-governmental organisations the world has ever known.
Martin
Luther came along and actually read The Bible, as created by the aforementioned
Council of Nicea. He realised that the
Church was not sticking to it and proposed a new “back to the Bible” version of
Christianity, Protestantism (because they were protesting against the Church).
In England,
King Henry VIII had fallen out with the Pope, who wouldn’t allow him to divorce
his older wife for the younger, sexier Anne Boelyn. He sided with Luther and created the Anglican
Church. There were now two versions of
Christianity: the “Catholic” variant and the “Protestant” variant.
This “rejecting
the established church” idea caught on and soon Protestant Christianity was
split into many sects, divided over trivial matters of doctrine, each of which
claimed all the others was “not really Christian”.
This is
pretty much where we are today.