At the conclusion of the Mass in St. Peter's Square, the Pope's countrymen will sing the traditional 'Stolat' (may you live for 100 years!), accompanied by Polish Radio's national orchestra.
The rest of the day will be like any Sunday for John Paul II, who does not celebrate his birthday but rather the feast of his patron, St. Charles (Karol), on November 4.
The two new Polish saints will be Bishop Joseph Sebastian Pelczar, 1842-1924, founder of the congregation of Handmaids of the Sacred Heart of Jesus, and Ursula Ledochowska, 1865-1939, founder of the Ursuline Religious of the Sacred Heart of Jesus in Agony.
The other two new saints are Maria De Mattias, 1805-1866, founder of the congregation of Sisters, Adorers of the Blood of Christ, and Virginia Centurione Bracelli, 1587-1651, founder of the Religious Daughters of Our Lady on Mount Calvary.
After Sunday's celebration, John Paul II will have canonized 489 blesseds in his close to 25-year pontificate.
Candidates for beatification must first have a reputation for holiness among people. Then, before their case is taken to Rome, a detailed diocesan investigation is carried out to verify that they lived "heroic" Christian virtue.
Finally, the beatification will take place if the candidate died a martyr --spilt their blood in defense of the faith -- or a miracle is verified as attributed to the candidate's intercession.
Verification of a second miracle attributed to a candidate opens the way for their canonization.
Verification of a miracle -- a scientifically inexplicable cure -- is carried out by a medical scientific commission and, finally, by a theological commission.