The world's first Slavic pope, who played what many believe was an important role in the collapse of communism, marked the occasion with the publication of a new memoir. He also called on a Catholic saint to help bring peace in the Middle East. "Don Orione, intercede, in particular, for peace in the Holy Land, in Iraq, and in other regions of the globe which are ravaged by war and bloody conflicts," he said.
The birthday celebration has raised inevitable questions about who will succeed the Polish-born pontiff -- who suffers from Parkinson's disease -- as leader of the world's 1 billion Roman Catholics. Many Vatican watchers say the time is ripe for a non-European pope, who would be the first since a few North African pontiffs reigned in the early days of the church.
There are always informal lists in Rome of "papabili" -- candidates who might be qualified to become pope. One name on all the lists is Francis Arinze, a cardinal from Nigeria. A black pontiff may seem novel to some, but experts say there's a reason Arinze makes all the lists of papal candidates.
Gerard O'Connell, a British journalist who covers the Vatican, told RFE/RL, "I've spoken to many cardinals, and many of them see the relations with Islam, the relations with the other religions, as a priority issue for the future pontificate." O'Connell has written a book about Arinze called "God's Invisible Hand."
O'Connell added that two of the biggest factors likely to be considered in the choice of the next pope are the growing gap between the world's rich and poor and the rising tensions between the Muslim and Christian worlds. He said the 74-year-old Arinze, in that regard, may be the perfect choice.
"Cardinal Arinze is a very good communicator. He is able to speak in a language that reaches people. He transmits a sense of joy and hope -- great joy comes out. He's not one of these doomsday people. And he's had 18 years heading the Vatican's office for dialogue, for relations with the other major religions of the world -- Islam, Hinduism, Buddhism, the traditional religions.," O'Connell said.
Since 1985, Arinze has headed the Vatican's office of interreligious affairs. As such, he has met with religious leaders around the world in an effort to promote cooperation and understanding.
Many Muslims accuse the U.S.-led war on terrorism and war in Iraq as basically being wars against Islam, a charge that Washington dismisses. But the Muslim perception of a "clash of civilizations" -- as a U.S. scholar has put it -- with the Christian world is nonetheless alive and well.
Moreover, Muslims and Christians have long been at war in Sudan. And Arinze's own country, Nigeria, is uneasily divided between Muslims and Christians -- a divide that some say could someday explode in violence.
O'Connell said cardinals in Rome tell him Arinze is thought of as the man who could possibly reconcile these two worlds. He said Arinze's message would be that the political manipulation of religion is always wrong. "It's not religion that's the driving force [of violence], it's the political manipulation of religion. If he were elected pope, he would bring this out very strongly: that the political abuse of religion is something that is not acceptable and that religious leaders should not countenance and should, in fact, separate themselves from," O'Connell said.
Another factor that may play in Arinze's favor is his perceived orthodoxy, which could go over well with the 120 or so cardinals who elect the next pope in a secret conclave. Most of those cardinals were put in place by John Paul, a religious conservative, and presumably will vote for a like-minded man.
Still, the election of a pope is always unpredictable. And there is an old saying that those who look most likely to become pope never do so: "He who goes into the conclave a pope, comes out a cardinal." But O'Connell said that's only partly true, and that at least two recent popes -- Pius XII and Paul VI -- were the favorites going into the conclave.
He added that with 82 percent of Catholics now living in the third world, the church seems bound by its own demographics to look beyond Europe and focus on helping to bridge the gap between the rich and poor. "This failure to overcome that gap, and to witness the silent death or the silent misery of so many people, will be a task that the new pope will have to bring in his mission," O'Connell said.
But for now, Karel Wojtyla is still running the Vatican. And if determination counts for anything, he'll be there for a good while yet.