Papal infallibility is related to two factors- on one hand, the fact that to err is human, and on the other, Christ's affirmation that to attain salvation it is imperative that one should accept and live his teaching.

To err is human. One aspect of this is that what is said or written in a human language can be misunderstood, misinterpreted, misconstrued. We know that this has happened to Christ's teaching itself.

From the Gospels it is clear that Christ founded a Church. But today, there are many Churches, holding and teaching contradictory doctrines. For instance, some Churches take literally Christ's words "This is my body" and believe that Christ's body is really present in the Eucharist, while other Churches deny it. What exactly did Christ mean? Here we see the need to have some means by which we can know Christ's true teaching.

Christ said to his disciples: "Anyone who listens to you listens to me; anyone who rejects you, rejects me, and those who reject me reject the one who sent me" (Luke 10:16). Acceptance of Christ and his teaching is therefore essential for salvation.

If then Christ's teaching can be misinterpreted, but is at the same time indispensable for salvation, shouldn't he have provided some means by which his teaching can be known without error?

He has actually done so. He has given his Church a means by which his teaching can always be known correctly, without error and misinterpretation. It is the prerogative without error and misinterpretation. It is the prerogative given to the Church, which we know as infallibility.

Infallibility resides in the Pope as Peter's successor and in the body of bishops together with the Pope as successors of the apostles.

In the well-known passage in Matthew (16:18-19) Christ not only gives Peter special powers and a position of preeminence among his disciples but also the assurance that his 'binding and loosing' will have heaven's approval which implies that he will be preserved from error.

After the resurrection, Christ entrusted to Peter the care of his flock. "Feed my lambs", "Feed my sheep" (John 20:15, 17). For so responsible and onerous a charge as that of tending Christ's entire flock he surely needs heavenly guidance and inerrancy.

Christ prays for Peter and guarantees him preservation from lapse and it is Peter who is to ensure that the steadfastness of others. "I have prayed for you, Simon, that your faith may not fail, and once you have recovered, you in your turn must strengthen your brothers" (Luke 22:32).

From the above texts we see that, on the one hand, Christ appoints Peter to a position of headship and leadership in the Church and, on the other, assures him that he would be preserved from error in the discharge of his duty of 'feeding' the lambs and sheep. It is this prerogative of preservation from error that the Church has understood as infallibility, a prerogative essential to the Church if it is to fulfil its obligations.

The traditional belief of the Church in respect of papal infallibility was thus summed up by Vatican I which defined infallibility: "The Roman Pontiff, when he speaks 'ex cathedra', that is, when he discharges his office as pastor and teacher of all the Christians, and, in virtue of his supreme apostolic authority, defines a doctrine concerning faith or morals that is to be held by the universal Church, through the divine assistance promised him in St Peter, exercises that infallibility, with which the divine Redeemer willed to endow his Church." (Denzinger-Schonmetzer,3074).

On the infallibility of the body of bishops, Vatican II states "The infallibility promised to the Church resides also in the body of bishops when that body exercises supreme teaching authority with the successor of Peter." (Dogmatic Constitution on the Church, 25).

It will be seen that infallibility is not impeccability. The Popes can fall into sin like anybody else. They can also make mistakes in matters that do not concern universal teaching on faith or morals. Infallibility, furthermore, is not a power to create new doctrines. It is a very specific and limited power. Its purpose is to preserve from error the teachings given by Christ to his Church.