Who was Marcion?

Marcion was born in Sinope (now Sinop in Pontus on the Black Sea in Turkey) and was the son of a wealthy ship builder. According to the Catholic Enyclopedia he was the son of a Bishop and a Bishop himself. The complete story from the account by Tertullian who wrote "Against Marcion" was that he disgraced himself in an affair with a woman, and was forced to leave his home town. The Catholic Encyclopedia admits that Tertullian often accused his enemies of scandals. The question is "How much of this is true?". My guess is that by making Marcion and his father Bishops, that the Church existed before Marcion right? But we are saying that the Catholic Church stole Marcion's 11 books and crafted them into Christianity. Where is the evidence that Christianity or the New Testament existed before Marcion's New Testament Canon written in AD 140?