Story highlights Pope John Paul II will be declared a saint

Pope John XXIII also achieved sainthood

John Paul II was the third-longest serving pope in history

The Roman Catholic Church will declare the late Pope John Paul II a saint, the Vatican announced Friday.

Pope Francis signed the decree Friday morning, the Vatican said. John Paul was pope from 1978 until his death in 2005, and was in a way the first rock star pontiff, drawing vast crowds as he crisscrossed the globe.

At his funeral, thousands of pilgrims gathered in St. Peter's Square and chanted "Santo subito" -- Sainthood now! The Polish-born pope was fast-tracked to beatification and became "the blessed" John Paul II barely six years after his death, the fastest beatification in centuries.

Pope John XXIII, who convened the Vatican II council in the 1960s, will also be declared a saint, the Vatican said

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No date has been announced for the canonization ceremony.

Pope John Paul II, the third-longest serving pope in history, died in April 2005 at the age of 84.

He had suffered from Parkinson's disease, arthritis and other ailments for several years before his death.

During his tenure, he became the most widely traveled pope in history and canonized more saints than any other pope.

His papacy included a lot of firsts. He was the first modern pope to visit a synagogue and the first pope to visit Cuba.

There are essentially three steps to becoming a Catholic saint after death.

First, the title "venerable" is formally given by the pope to someone judged to have exhibited "heroic virtues." Second, a miracle must be attributed to the deceased person's intervention, allowing beatification. Canonization -- or sainthood -- requires a second attributed miracle.

In 2010, Pope Emeritus Benedict XVI approved John Paul's first reported miracle: a French nun supposedly cured of Parkinson's disease.

Sister Marie-Simon-Pierre, a nun whose order prayed to the pope after he died, said she was cured of the disease, an ailment that also afflicted John Paul.

The second miracle reportedly occurred in Costa Rica, where a woman said she recovered from a severe brain injury thanks to the intervention of John Paul, sources told CNN Vatican analyst John Allen.

Patrick Kelly, executive director of the Blessed John Paul II Shrine in Washington, explained the church's process for investigating reported miracles.

"A team of doctors first examine the miracle. Secondly, the team of theologians look at the miracles, and then they discuss amongst themselves the legitimacy and all the facts surrounding the miracles," he said.

Despite being so beloved, John Paul didn't live up to expectations at a crucial moment in the church's history, as revelations of sexual abuse scandals involving thousands Catholic priests erupted across the world in the early 2000s, critics say.

In the United States alone, the scandal involved more than 16,400 victims or alleged victims and cost the church $2.6 billion in settlements, therapy bills, lawyers' fees and care for priests removed from ministry, according to the U.S. Conference of Catholic Bishops.

John XXIII was famed for calling the Second Vatican Council in 1962, which ushered in great changes in the Roman Catholic Church's relationship with the modern world.

He was pope from 1958 to 1963, and was beatified by Pope John Paul II in 2000.