According to Catholic doctrine, Jesus made Peter his successor on earth. Peter then went to Rome to spread Jesus' message of uncompromising love and some "end of days" spiel and ended up martyred. As the first bishop of Rome, Peter laid the foundations for Catholicism, the term Catholic meaning universal. The Church was the sole judge as to whether views that were heretical or orthodox. From Jesus to Peter to John Paul II, that's the history of Christianity in a nutshell. At least that's one take on it. Catholicism is merely a sect of the overall Christian belief system, and there are many others along with it.
I was raised Catholic as I'm sure many of you were as well. The Church views the history of Christianity as its and its alone. Any movements outside the Church are not really Christian because they are not Catholic. Arians, Greek Orthodox, Coptics and Protestants are not alternative views of Christianity, but are heresies. If you were raised non-Catholic, have no fear, you are not destined for Hell. When you die, your soul is destined for an eternity of limbo. Neither Heaven, Hell nor even purgatory, just limbo. Those who are in trouble are lapsed Catholics, like me. We know the eternal truth the Church preaches and still reject it, so it will be our souls that stoke eternal fires in Satan's dark underworld. Simple, isn't it.
Of course, we all know the history of Christianity is not one unbending line from Jesus to the current pope. What about Luther or Henry VIII or Wyclif? How about newer movements like the Mormons? Are they not Christian because they deviate from the Jesus to John Paul II line put forward by the Vatican?
Christianity is a religion that will never be one thing to all people. So no one can say that Rev. Ian Paisley's version is wrong while Mother Theresa's is right. Because there was never just one Christianity, there will never be just one. This means that however demented Paisley's interpretations of the Gospels are, they are just as valid as those of Thomas Aquinas.
As it is with Christianity so is it with other religions, including Islam. There is no one Islam. There was, but that ended the minute the Prophet Mohammed died. There is Sunni Islam and Sh'ite Islam, there is Nation of Islam and then there are groups like the Taliban. Following the attacks on New York last month, Muslims the world over were quick to denounce Osama bin Laden and the Taliban as anti-Muslim. That is wrong. Their interpretation of Islam may be quite different from the vast majority of Muslims, just like Paisley's Christianity is different from that of my mom, but it is still a valid interpretation.
Islam is not in question here. By forcing Muslims to defend and explain their religion to the non-Muslim world, we are belittling their faith while simultaneously driving a wedge between the Islamic world and the rest of the world. No one asked Catholics in New Zealand to defend Catholicism in the wake of the Second World War because Hitler and many other Nazis were raised Catholic, so don't ask your Muslim neighbour to defend himself because a handful of people committed these atrocities.
And in case you were wondering, the souls of lapsed Catholics are made of asbestos. That's why they can burn for an eternity.