Go to the channel "Reason and Theology", or email the host.
Setup a debate/listen to the debates.
Give a defense for why Catholicism isn't Christianity.
There are no good arguments though, just warning you now.
None of those are good arguments. They're either misstatements of Catholic teaching, or just stuff you made up that Christians believed for 1500 years before you decided that Christ and the Apostles, and everyone who came after them were bad teachers and couldn't teach Christian dogma (e.g., baptism).
You just want to be your own authority. But this board isn't the right forum to have a deep theological discussion. If you're interested in that, I already told you what to do.
PATER NOSTER