People tend to believe what they want to believe. And they tend to believe what they want to believe about other religions.
Catholic theological doctrine, like all forms of theology, is a closed system. It only makes sense when compared within the assumptions of that theology. From a theological standpoint, you can ask whether a specific doctrine (or dogma) is internally consistent. But it's somewhat hard to compare different theologies with each other.
The Catholic theology starts from the premise that the 12 Apostles spoke the truth about Jesus Christ (there was not a New testament until some years later, so scripture could not have been the original authority). Protestant doctrine holds that the original Apostles are the authority and that the New Testament is the best source for determining dogma. Catholic and Orthodox hold that the teaching was conveyed through the church and the bishops, and that this line of authority holds true. The Catholics ultimately unified around the bishop of Rome (aka the Pope). Orthodox hold that each Bishop is an authority as long as that person remains true to tradition.
Oddly enough, this line of secession is not merely a Christian issue. The split between Sunni & Shiite Muslims is similar. The Islamics of the Sunni tradition hold that the writings of Mohamed (sp?) are the sole authority (much as the Protestant holds to the Bible). The Islamics of the Shiite tradition hold that one of Mohamed's cousins (i think it was a cousin?) carried a sort of apostolic tradition. It's why the religious leaders in Shia are considered authorities, while the Sunni's denounce their authority. The Shia would be closer to the Orthodox in this case, in that the religious authorities are closer to bishops, with no correlary of a central authority bishop like the Pope.
Anyhow, just a few religious tidbits.