Pope Francis believes 'papacy is for life,' says historian-biographer

"He's spoken various times about this," Ivereigh told Fox News in an interview. "He's saying that for him, the papacy is for life." 

"It's really important in a world where there's a kind of cult of health and youth," added Ivereigh, "that we say, 'No, there is a mission that God gives you, which is for life.'"

Here in St. Peter's Square, a nightly rosary vigil, led by one of the cardinals of the curia, is keeping the fires of faith lit that Francis will recover.

Yet Ivereigh admitted, "There's an anxiety. There's a sense of uncertainty."

History has helped provide that anxiety and uncertainty. Francis' predecessor, Pope Benedict XVI, resigned in 2013, the first pontiff to do so in more than 500 years.

But then there are those who may wish he would resign. 

Bishop Joseph Strickland, a vocal critic of Pope Francis, wrote an open letter to the College of Cardinals urging them to choose wisely in the next conclave.

He went on, "Your Eminences, I would also recall to your mind that you have a grave obligation before God to refuse to give assent to the election of any candidate who does not fulfill the conditions established by divine law."

Wrote Strickland, "If a public heretic, or a man who is reasonably suspected of being a public heretic, receives sufficient votes, faithful cardinals have an obligation to refuse to accept the validity of his election."

Said Ivereigh, "He proclaims the truth, and at the same time he heals and loves. And in fact, the truth that he proclaims is a healing truth and the healing that he does - it communicates the truth of who God is."

In his 12 years as bishop of Rome, Pope Francis has continued to mold the Catholic Church in ways that are very different from those of his predecessors. 

First, he worked to clean up the mess in the Vatican Bank, and he expanded the College of Cardinals, creating cardinals in faraway places that had never had the high position before, such as in San Diego. 

He also elevated a woman to one of the highest-ranking positions in the Vatican: Sister Raffaella Petrini, the new president of the Pontifical Commission for Vatican City State and president of the Governorate of Vatican City State.

From working with the pope on projects, Ivereigh knows the Holy Father is a workaholic. And he believes this current health crisis will be resolved in a positive way.

"I think the immediate future is all about him coming out of the hospital, getting back to his residence in Santa Marta for what everybody expects will be a long convalescence," Ivereigh said. "The doctors, I think, are pretty clear about that."