It also goes by interpretation, which can really make things a big problem. Which is why all of tthose denominations exit.

First came Jesus and he told Peter that he would be the rock of which the church would be founded.

Early Christians had to go in hiding a LOT.

Then Constantine came along and allowed Christianity to last due to a vision he reported to have seen of a cross. The early church begins to develop finally after years of being tortured by the Roman Empire.

After Constantine, Justinian came along, and here's where problems start. Justinian took what Constantine one step further. He made Christianity the national religion, so that anyone who wasn't a Christian had to pay a special tax among other things. Saint Augustine was against this and wrote 'The City of God' which defines that there should indeed be a difference between church (or any religion for that matter) and state. Justinian basically ignored it though. By making it a national religion, big time money goes to the churhes which instantly begin to prosper from it. Problem is that all the people of the Roman Empire recall hearing different teachings than the others. So they all get together for a conference and figure out what they believe to be the true writings and get rid of what the majority considered heresy. And thus... Catholicism was made.

Now I have to back up a bit to Constantine. He had built a second capital for the Empire in Constantinople, in which he founded a church as well while there was already one in Rome. And when the Empire splits up later, Catholics and Orthodox split as well.

Then fast forward to 1500-something Martin Luther realizes that the Catholic church is corrupt because of indulgences and worshipping relics and odd rituals and ruitines, and penance.

The rest would take even longer to explain So I'll let you go figure the rest out.