In the last 900 years, only three popes have been made saints by the Catholic Church. Many experts believe that John Paul II, the man who canonized more saints than all other popes combined, will be one of those exceptions.
Cardinal Edmund Szoka, the president of the Pontifical Commission for Vatican City State, said, "In my opinion, he's a saint. He's a very, very holy person."
Szoka is a member of the powerful Vatican Congregation for the Causes of Saints, which considers and votes on candidates for sainthood before forwarding its recommendations to the pope.
"I certainly have no doubt that his cause will be introduced," he said.
One of the reasons so few popes have been made saints in the last millennium is that they did not live selfless lives, as Jesus did, nor did they display humility, nor were they martyred for their faith -- all criteria for sainthood.
So what might influence the church to make John Paul II a saint once the required period of five years has passed after his death?
Not necessarily the obvious things, experts say. Even the hallmarks of John Paul's papacy -- the travel, his contribution to the fall of communism -- would not be considered as important as gestures that, at the time, may have seemed much smaller than his successes.
"His greatest gesture may not be standing up the way he did to communism -- although that can be considered, you know, good versus evil -- but forgiving the man who shot him," said Ken Woodward, an authority on the Catholic Church. "That's what Christ would do. That's what Christ did do. 'Father forgive them, they know not what they do.' "
And consider another criterion: What a person has gone through to practice his or her faith.
When Poland was under Nazi control, the man who would become pope worked as a laborer to avoid arrest while studying in an illegal seminary to enter the priesthood. He hid in a basement apartment to avoid Nazi conscription.
Many say John Paul II was a man who suffered for his faith.
"You don't all of a sudden become holy," said Woodward. "You learn from experience, and … there should be some suffering. After all, this is a religion that has a guy dying on a cross as its central symbol. So they'll look for, 'Did he suffer?' "
John Paul II's affliction with Parkinson's disease has also been cited as evidence of his determination in the face of suffering.
"I mean, here's a man who is vigorous and he's been brought low," said Woodward. "The mind is alert. He's got an unfinished agenda and he can't do anything about it."
But what about the criticism of John Paul II? He did get his share, aimed at his positions on the role of women in the church, against birth control and against allowing priests to marry. Some critics within the church also have said he was too authoritarian in his papacy.
But many papal experts say the investigation of John Paul II's life would not be an assessment of his administration -- what he did or didn't achieve as Pope -- but would focus on the simpler personal details of his life.
But he was a man whose public achievements shook the world, a man who spoke out against poverty, hunger and injustice.
Szoka says that John Paul II embodied the virtues of faith, hope, charity and love and was a living example of justice, prudence, temperance and fortitude.
"It's hard to say what will emerge as his most predominant virtue," said Szoka. "What will emerge is how outstanding he has been in all these virtues to a very, very exceptional degree. All those things together convince me that he is a saint."
ABC News' Bob Brown originally reported this story on "Good Morning America" Weekend edition.