Does papal infallibility mean the Pope can never make a mistake or sin?
No. Papal infallibility does not mean that the Pope is personally sinless (impeccable) or that every personal opinion or casual interview he gives is free from human error. The Pope goes to confession like every other Catholic.
Infallibility is a specific spiritual gift promised by Christ to protect the Church from error when proclaiming essential truths of faith or morals. The Pope exercises this charism only in very precise circumstances: when he speaks 'ex cathedra' (from the chair of Peter) as the universal pastor and teacher of all Christians, solemnly defining a doctrine concerning faith or morals that must be held by the whole Church.
In such cases, the Holy Spirit prevents the Pope from committing the universal Church to an error. This gift exists not for the Pope's personal prestige, but to assure ordinary believers that the truth of the Gospel remains pure and dependable throughout history.
Sources
- Catechism of the Catholic Church, paragraph 891
- Luke 22:32
Awaiting review by the chaplaincy. Written in our own words; the Church's own texts are the authority.