What about other religions? Islam and Judaism come to mind, but there are also non-abrahamic religions that advocate faith, hope and love. Why is are you exclusively a Christian and not a Muslim, a Jew, a Buddhist or a Pagan? Why are you a Catholic instead of a Protestant? If you were born in China in the early 20th century, would you be a Catholic? If so, why? If not, why are you a Catholic here and now?
Because the Catholic Faith is true. But this is getting off topic.