Pope John XXIII “the Good” (left) and Pope John Paul II “the Great.”Wikimedia Commons

Two of the most beloved popes of the Roman Catholic Church will be canonized Sunday in an unprecedented ceremony expected to draw more than a million people to Rome.

Both Pope John Paul II “the Great” and John XXIII, the "Good Pope” tore down walls and were known for their charismatic personalities.

Yet the historic sanctification has already stirred controversy. Critics scrutinizing the papacies argue that sainthood for both popes was at least too hasty.

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The embalmed body of John XXIII resides in a glass coffin in St. Peter’s Basilica.Rossella Lorenzi

Only the third pope (after Blessed Innocent XI, who died in 1689, and St Pius X, who died in 1914) to be given the honor of resting in a glass coffin inside St Peter's Basilica, John XXIII is best known for the reform of the Catholic Church during the Second Vatican Council (1962-65).

Born in northern Italy to a family of sharecroppers on November 25, 1881, the third of 13 children, Angelo Giuseppe Roncalli was elected pope on Oct. 28, 1958, at the age of 76.

He was the first pontiff to take the name of "John" in more than 500 years. Previous popes had avoided the name to avoid confusion with the 15th-century schismatic antipope John XXIII.

Roncalli’s papacy lasted less than 5 years -- he died of stomach cancer June 3, 1963 -- but left an indelible mark by putting aside doctrinal issues and focusing on the modern world’s trends.

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John XXIII in the first year of his papacy. Wikimedia Commons

"Going home, you will find your children. Give them a caress and tell them 'This is the caress of the pope.'"

Pronounced by John XXIII on the opening night of the Second Vatican Council, these are remembered among Catholics as John’s most famous words. Indeed, they symbolize the pope’s revolutionary interpretation of his role.

John, the first pope to smoke cigarettes, put aside the Church’s rigid and often obscure language and reached people’s hearts with a simple, spontaneous and paternal approach. This attitude earned him the name “the Good Pope.”

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John XXIII appears on the the gestatorial chair, the ceremonial throne on which popes were carried on shoulders until 1978 (left). The pope waves on the day of his coronation (top right) and signs his last encyclical letter titled "Peace on Earth."Wikimedia Commons

Despite his short reign, Pope John XXIII widened the Church’s horizons by calling the Second Vatican Council, the first ecumenical council in a century. John didn't live to see the council through, yet he launched the process that modernized the Catholic Church.

The Council produced revolutionary reforms which included the use of local language rather than Latin for Mass, ecumenical efforts toward dialogue with other religions, and a new, more communicative approach to the world.

Aside from Vatican II, John XXIII is best remembered for his last encyclical letter titled "Pacem in Terris," ("Peace on Earth") in which he asked "all men of good will" to work for peace.

Beatified in 2000 in a ceremony led by Pope John Paul II, John XXIII will be made a saint although only one miracle --instead of the two normally required -- has been attributed to him.

This rush to sainthood, which has also involved John Paul II, has been the subject of a harsh debate in the 1.2 billion member Church.

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The funeral of Pope John Paul II. Blues Brother/Wikimedia Commons

If the road to sainthood may seem fast for John XXIII, it is ultra speedy for Pope John Paul II. The Polish Pope is setting a record for modern times by becoming a saint only nine years after his death.

Indeed, calls for “santo subito” (“saint now”) erupted already during his funeral, which was attended by about 2 million people, heads of states and dignitaries from at least 155 countries.

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Wikimedia Commons

Born Karol Wojtyla on May 18, 1920, in Wadowice, Poland, a town near Krakow, John Paul II has been the first pope of the third millennium, and the third-longest serving Pope, having led the Roman Catholic Church for 26 years.

Elected pope in 1978 at the age of 58 (the youngest pontiff in 132 years) John Paul was a man of contrasts, who championed human rights and challenged dictators. At the same time, he was criticized for his conservative vision of theology.

He was the first non-Italian Pope since Adrian VI in 1522, the most traveled pope in history, and the most hospitalized Pope.

Over the years, he underwent nine operations, surviving an assassination attempt in 1981. He developed arthritis and Parkinson's disease and died on April 2, 2005.

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John Paul II at a papal audience in St. Peter's Square, 1985.James G. Howes/Wikimedia Commons

The only Pope whose life was portrayed in a comic book -- Marvel Comics published a pope biography in 1983 -- John Paul became the first pontiff to wear trousers under his vestments and the first pope to wear contact lenses.

The less-formal style he adopted from his predecessor John Paul I, contrasted, however, with his rigid traditionalist moral stance on issues like contraception, divorce, gay marriages and abortion.

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Pope John Paul II appears in New York City in 1979.Thomas J. O'Halloran/Library of Congress/Wikimedia Commons

The most traveled pope in history -- he visited nearly every country in the world which would receive him -- John Paul II was the first pontiff to meet a Kremlin chief, to set foot in a mosque and to visit a synagogue.

In 2001, he was the first Pope to visit Greece since the Schism of 1054, offering an apology for "sins of action and omission" by Roman Catholics against Orthodox Christians.

He is also the first pope to visit the memorial at Auschwitz, Poland, to victims of the Holocaust.

In the document "We Remember: A Reflection on the Shoah (Holocaust)," John Paul expressed remorse for the cowardice of some Christians during World War II. However, he defended the actions of wartime Pope Pius XII.

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John Paul II toward the end of his papacy in 2004.Radomił Binek/Wikimedia Commons

In 2000, in one of the most criticized ceremonies of his papacy, he beatified the much-attacked Pope Pius IX, known his frequent anti-Semitic speeches. Reigning from 1846 to 1878, Pius IX confined Rome's Jews to a ghetto and called them "dogs."

Toward the end of his papacy, John Paul II was questioned about having done enough to respond to the church sex abuse scandal, specifically regarding the activities of the Mexican founder of the Legion of Christ movement, Marcial Maciel Degollado, who lived a double life as a drug addict who sexually abused minors and fathered children while being held in great consideration by the pope and his aides.

The Mexican priest was disciplined by Pope Benedict XVI in 2006 and died two years later.

Others criticized John Paul’s decision in 2004 to give Cardinal Bernard Law, who was forced to resign in 2002 as archbishop of Boston after the clerical sex abuse scandal hit the United States, a prestigious post as head of a basilica in Rome.

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The list of popes made saints begins with St Peter, traditionally regarded as the first leader of the church after Christ’s death.Rossella Lorenzi

Despite the critics, more than 1 million people are expected to attend the historic canonization on Sunday.

John XXIII, the hero of the church's progressive wing and John Paul II, a giant for the Catholic conservatives, will be the 79th and 80th popes of the Roman Catholic Church to become saints.

The list begins with St. Peter, and in the last 1,000 years only seven pontiffs have been made saints, including John Paul II  and John XXII.

To add to the uniqueness of the event, it will be the first time in the Church's 2,000-year history that two popes are made saints at one time.

The canonization will be attended by two other popes -- the reigning Pope Francis and the Pope emeritus Benedictus XVI.