Hey hey, first established Christianity had no particular sect. Catholicism was part of a split - which included a change of doctrine on Catholic part. The Christian sect that follows the original ideas most closely is Orthodox (Greek/East European and also closely resembled by Egyptian Coptic), while Catholicism proposed a lot of new rules and produced several new methods of reading into the biblical episodes. Orthodox was not a split from Catholicism - the split occurred simultaneously =) (some accepted the idea of catholic - world religion - some did not).I think Arnus is Muslim too.
I'm always confused as to why people don't think Catholics are Christians. I remember one time I was waiting for the bus at school and this random old lady who was Baptist came up to me and asked all sorts of questions. Told her I was Catholic and she said something like so you're not Christian. The first form of established Christianity was Catholicism, most every form of Christianity derived from Catholicism. The first split occurred when the Eastern Orthodoxes split from Roman Catholics. Then the next split was from the Protestant/Martin Luther movement which gave way to Christian denominations like Protestants, Lutherans, Baptists etc.
But I do concur - Catholics are Christians =).
That and I am not religious by the way, just some history for ye.