Christianity--and probably most religions--can be broken down into two component parts. On the one side you have its mythos. This is the broad story on which it's based.
For Christianity, that's the story of redemption: how Jesus, before the world began was the Son of God, how He was born into the world, how He lead a blameless life and yet He was put to death, and how He rose again and ascended to heaven, and how one day He will return to judge the living and the dead. That's the mythos of Christianity.