Question:
Answer:
While the Church has never formally defined canonization as an act of infallibility, the definitive and therefore infallible nature of this teaching is rooted in its necessary connection with the dogma of the communion of saints, which is professed in the Apostles’ Creed and also—in summary form—within the Nicene Creed’s profession of “the one, holy, catholic, and apostolic Church.” As the Catechism of the Catholic Church (CCC) provides,
The supreme degree of participation in the authority of Christ is ensured by the charism of infallibility. This infallibility extends as far as does the deposit of divine Revelation; it also extends to all those elements of doctrine, including morals, without which the saving truths of the faith cannot be preserved, explained, or observed (CCC 2036, emphasis added).
St. Thomas Aquinas elaborates:
Since the honor we pay the saints is in a certain sense a profession of faith, i.e., a belief in the glory of the saints, we must piously believe that in this matter also the judgment of the Church is not liable to error (Quodlib. IX, a. 16).
Because the Pope is formally decreeing that all Christians are to believe that a certain person is in heaven, and thus can be prayerfully invoked in a fruitful manner, the certitude of his decree also flows from the pope’s divinely given charism of papal infallibility.