There has been good reason that popes haven't stepped down over past centuries, given the possibility for divided allegiances and even schism. But the Vatican insists that, while the situation created by Benedict's retirement is certainly unique, no major conflicts should result.
"Knowing Benedict XVI, it won't be a problem," Giovanni Maria Vian, the editor of the Vatican newspaper L'Osservatore Romano, said in an interview. "According to the evolution of Catholic doctrine and mentality, there is only one pope. Clearly, it's a new situation, but I don't think there will be problems."
Critics aren't so sure. Some Vatican-based cardinals have privately grumbled about the decision, saying it will make it more difficult for the next pope with Benedict still around.
Swiss theologian Hans Kueng, Benedict's onetime-colleague-turned-critic, went even further: "With Benedict XVI, there is a risk of a shadow pope who has abdicated, but can still indirectly exert influence," he told Germany's Der Spiegel magazine last week.
The Vatican spokesman, the Rev. Federico Lombardi, said Tuesday that Benedict himself decided on his name and wardrobe choice in consultation with others, settling on "Your Holiness Benedict XVI" and either "emeritus pope" or "emeritus Roman pontiff."
Lombardi said he didn't know why Benedict had decided to drop his other main title: bishop of Rome.
In the two weeks since Benedict's resignation announcement, Vatican officials had suggested that Benedict would likely resume wearing the traditional black garb of a cleric and would use the title "emeritus bishop of Rome."
Adding to the concern is that Benedict's trusted secretary, Msgr. Georg Gaenswein, will be serving both pontiffs - living with Benedict at the monastery being converted for him inside the Vatican, while keeping his day job as prefect of the new pope's household.
Asked about the potential for conflicts given the existing divisions within the Vatican bureaucracy, Lombardi was defensive, saying the decisions had been clearly reasoned and were likely chosen for the sake of simplicity.
Benedict himself has made clear he is retiring to a lifetime of prayer and meditation "hidden from the world." However, he still will be very present in the tiny Vatican city-state, where his new home is right next door to the Vatican Radio transmitter and has a lovely view of the dome of St. Peter's Basilica.
Kueng said it was a mistake for Gaenswein to serve both men and for Benedict to remain so close to the center of action.
"No priest likes it if his predecessor sits next to the rectory and watches everything he does," Kueng was quoted by Der Spiegel. "And even for the bishop of Rome, it is not pleasant if his predecessor constantly has an eye on him."
However, others reasoned that Benedict's retirement plans and title were in keeping with those of other retired heads of state.
"I was somewhat surprised that Benedict would still be called 'His Holiness' and would wear white, but it's akin to the former U.S. presidents being addressed as 'Mr. President,' " said the Rev. James Martin, a Jesuit writer and editor. "It's a mark of respect for the former office he once held."