More than 2 million people are descending on Rome to attend the formal installation on Sunday of Pope John Paul II and John XXIII as saints of the Catholic church.

In different ways, both men made their marks on history.  John XXIII may be the most consequential pope in the last 500 years.  He called the Second Vatican Council that changed the liturgy, making it more accessible to worshipers.  He also began an ecumenical movement that reached out to heal the historic schism between Rome and the Orthodox faith, declared that Jews should be held blameless for Christ's crucifixion, and dialogued with Protestants.

John Paul II was not only a good and holy man; he was a seminal political figure, one of the most important of the 20^th century.  Along with Ronald Reagan and Margaret Thatcher, he helped to bring down the Soviet Union.

And now, after a complex process, both will be enshrined in the Book of Saints:

The Italian capital is bracing for the arrival of more than 2 million pilgrims to help celebrate the formal declaration that John XXIII and John Paul II — perhaps the two most beloved popes of modern times — will be declared saints.

Sunday's date has been marked on the calendar of devout Catholics since it was announced last September by Pope Francis, whose own popularity rivals that of the two soon-to-be saints barely a year into his papacy.

The massive influx, fueled in part by 1,700 buses, 60 flights and a half-dozen special trains for pilgrims from John Paul's native Poland, is likely to be the largest gathering in Rome since John Paul's funeral eight years ago.

"John XXIII and John Paul II were so revered by both Catholics and non-Catholics that it is expected that shining a light on them in this way will help draw people together," said the Rev. Alistair Sear, a retired church historian who met both popes.

"The two popes appeal to different segments of the church, which means Sunday should be a moment of unity and good feeling for a church that can use it."

John became pope in 1958 and convened the Second Vatican Council, which tried to make the Mass and liturgy of the 2,000-year-old church more accessible to the 20th century. He died in 1963, and his legacy included rifts among churchgoers who felt he was too liberal in his revamping of church rituals.

John Paul, who was Polish and at the time was the first non-Italian pope in more than 400 years, became pope in 1978 and is considered one of the more charismatic popes in recent times.

He survived an assassination attempt in 1981 to become a major figure in the Cold War that pitted democratic countries against the communist dictatorship that was the Soviet Union. His own Poland was a captive of the state for decades.

John Paul urged nations to confront the Soviet Union as an evil empire that denied the most basic of rights, including that of freedom of religion. He notably apologized for the Roman Catholic Church having imprisoned Galileo in seeking to portray the church as not hostile to science, and apologized to Jews for the history of Christian anti-Semitism, said Holly Grieco, associate professor of religious studies at Siena College in Loudonville, N.Y.

It could be said that Pope John XXIII brought the Catholic church into the 20^th century, and his reforms were the most consequential in centuries.  The impact of Vatican II is still being felt today.

Pope John Paul II's influence will continue for many years; most of the cardinals in the governing body of the church were named by him.  But his legacy will no doubt be his steadfast support for freedom in his native Poland and elsewhere in Eastern Europe.