The Catholic Church’s teaching on papal infallibility is one which is generally misunderstood by those outside the Church. In particular, Fundamentalists and other "Bible Christians" often confuse the charism of papal "infallibility" with "impeccability." They imagine Catholics believe the pope cannot sin. Others, who avoid this elementary blunder, think the pope relies on some sort of amulet or magical incantation when an infallible definition is due.
The first Christians had no doubts about how to determine which was the true Church and which doctrines the true teachings of Christ. The test was simple: Just trace the apostolic succession of the claimants.
Apostolic succession is the line of bishops stretching back to the apostles. All over the world, all Catholic bishops are part of a lineage that goes back to the time of the apostles, something that is impossible in Protestant denominations (most of which do not even claim to have bishops).
The Catholic Church bases her teaching upon one source: The word of God. This divine revelation is transmitted in two ways: through Scripture and apostolic tradition. Many assume that only the writings of the apostles are the word of God. However, their oral transmission of the faith is also considered the word of God (1 Thess. 2:13). Few Protestant groups today accept the validity, let alone the authority, of tradition. In fact, many believe that Scripture is the only definitive source of divine truth.
At Catholic Answers we are often asked which Bible version a person should choose. This is an important question about which Catholics need to be informed. Some have been given very little help about how to pick a Bible translation, but keeping in mind a few tips will make the decision much easier.
"Who does not see that knowledge precedes faith? Nobody believes unless he knows what to believe."
~ Augustine of Hippo, convert, bishop, theologian, Father and Doctor of the Church, Saint; noting that the assent of faith is a rational act; before it can be made, it must be known for certain that there is a God, that He has spoken, and that what He has spoken is known. (see "Science and the Church")