Church teaching can be divided into multiple categories. Dogma, the highest form of Church teaching, is an infallible declaration of a certain truth in the matters of faith or morals, as we touched on earlier. When the Church teaches from the extraordinary magisterium, she teaches infallibly. Only the pope can define an infallible teaching on his own. While for the ordinary magisterium, the Church must have the consent of all the bishops, the pope can define a dogma regardless of what the rest of the bishops in the world think about it.
Infallibility is not impeccability (inability to sin). The pope is a human being who has the effects of Original Sin just as you and I do. An infallible teaching is not the result of the pope’s personal conduct, but of his office. As long as a president of the United States is president of the United States, he has the powers that come with the office, regardless of his integrity as a human being.
Infallibility does not imply that the pope goes out on a whim and proclaims some obscure thing to be true. No, everything that popes have defined (i.e. declared to be infallibly true) are truths that most Catholics held for centuries before their formal definition. For example, most Catholics had believed that Mary was immaculately conceived since the early Church, with fathers and doctors of the Church, such as St. Ambrose (Sermon 22, 30), St. Hippolytus (Orantions Inillud, Dominus pascit me, circa A.D. 235), St. Augustine (Nature and Grace 4, 36, A.D. 415), and others, affirming that the Blessed Virgin Mary was conceived without Original Sin. However, as we noted in the section directly above, the Church does not defend the truth until it is being attacked, and so she did not define the dogma of the Immaculate Conception until 1854, when calumnies arose, trying to defame the Blessed Virgin.
Therefore, infallibility differs markedly from inspiration (as in how the authors of scripture were inspired in their authorship of the bible). Infallibility is meant to preserve sacred teaching, while inspiration is meant to put it forth. Infallibility is primarily on the defensive, while inspiration is primarily on the offensive. God gave men Divine Revelation through inspiring the sacred authors, while He protects that Divine Revelation through the pope’s use of infallibility. Infallible teachings, therefore, like all Church teachings, are not an example of the Church fabricating truths. They are in fact actions undertaken to safeguard the Deposit of Faith which God has given His Church.
One common way some attempt to undermine the Church’s stance on papal infallibility is by claiming that the Church invented the doctrine at the First Vatican Council in 1870. At this time, Pope Bl. Pius IX defined papal infallibility to be true, but he was simply confirming what Catholics had held from the beginning. As in the definition of the Immaculate Conception, Bl. Pius IX defined papal infallibility because it was under attack, particularly from the forces of scientism and relativism.
Even what the pope says regarding faith and morals when not speaking ex cathedra is not considered infallible. Popes have also disagreed with each other on applications of certain dogmas and doctrines. But these disagreements do not disprove or in any way undermine the pope’s infallibility. If anything, they emphasize the Holy Spirit’s power and humility in that He works through fallible human beings to proclaim Himself.
Scripture also supports papal infallibility. The Church is the “pillar and bulwark of the truth” (1 Tim 3:15). The bulwark of the truth cannot err when she teaches truth. In Acts 10, Peter teaches definitively that the uncircumcised do not require circumcision to enter the Church (Acts 10:34-43). Subsequently, “the Holy Spirit fell on all who heard the word” (Acts 10:44). Then Peter “commanded” the Gentiles present to be baptized (Acts 10:48). St. Peter later recalls that the Holy Spirit descended on the hearers “just as on [the apostles] at the beginning” (Acts 11:15). St. Peter speaks with authority, like Christ did, as one who has received the Gospel, and seeks to imitate his Lord.
One common scripturally-based objection to papal infallibility is that St. Peter refused to eat with Christians of Gentile origin, so as not to offend some Jews who were with him. St. Paul rebuked him for this action, and St. Peter repented of his ways. But this occurrence does not disprove papal infallibility. It only confirms the pope’s peccability. Christ promised that the Holy Spirit would guide the Church “into all truth,” but not that the apostles or anyone else would be without sin themselves (Jn 16:13). Our Lord did not establish His Church for her to become a teacher of error.
Some will say that St. James, son of Zebedee, led the council of Jerusalem, recounted in the book of Acts, so that St. James was really the leader of the apsotles, not St. Peter. But even ignoring the manifold other evidence that St. Peter was indeed the leader of the apostles, including Christ’s words, St. James’ words do not suggest that he led the Council of Jerusalem. At the Council, St. James exhorted those present, in the imperative mood, to “akousate [(listen)] to” him (Acts 15:13). Moreover, critics of St. Peter’s supremacy will say that James has the final say on the council: “Therefore my judgment is that we should not trouble those of the Gentiles who turn to God” (Acts 15:19). Firstly, using the imperative mod does not connote supremacy. Anyone trying to get others to listen to them will likely use the imperative mood, but this does not suggest that the person has any authority over anyone else (Cathoilc Answers: Karlo Boussard). Moreover, St. James makes a pastoral proposal, while St. Peter spoke on matters of doctrine: that Gentile converts do not have to be circumcised. St. Peter clearly led the council, not St. James, because St. Peter was the prince of the apostles, the vicar of Christ on earth.
But while only the pope’s declarations ex cathedra are infallible, the Catholic faithful have the obligation to submit to the teaching of the Church, even in the teaching of the ordinary magisterium. “In matters of faith and morals, the bishops speak in the name of Christ and the faithful are to accept their teaching and adhere to it with a religious assent” (Lumen Gentium no. 25). The Church also teaches that all “judgments made by [the pope] are sincerely adhered to, according to his manifest mind and will” (Lumen Gentium no. 25). Therefore, even when the pope does not teach ex cathedra, Catholics are to treat him with due reverence because of his unique and holy office. This declaration does not mean that we must treat all the pope’s words as sacrosanct, for, again, he is a fallible human being. But we must assent to all he teaches infallibly, as well as all he teaches in union with the other bishops on the matters of faith and morals, which are manifestations of the Church’s faculties which enable her to know and to love: “[h]is mind and will in the matter may be known either from the character of the documents, from his frequent repetition of the same doctrine, or from his manner of speaking” (Lumen Gentium no. 25).
One recent decision of the Church which has caused much uproar in terms of the Church’s claim to teach without error regarding faith and morals is the 2017 change to paragraph 2267 of the Catechism, regarding the death penalty. The pre-2017 Catechism allowed for the death penalty in extreme cases as a means of safeguarding the common good. The new Catechism bans the death penalty on the grounds that “there is an increasing awareness that the dignity of the person is not lost even after the commission of very serious crimes” (CCC 2267). This change in the Catechism, however, does not reflect a change in fundamental Church doctrine. The Church never taught that it was okay to murder, nor does she now say that killing is always wrong even in the case of self-defense. This change in the Catechism is one of discipline (i.e. giving up meat on Fridays) rather than one of the Church’s stance on an objective truth.
In other words, Pope Francis’ change to the Catechism is not a doctrinal change, but a change in prudential judgment. For example, Pope St. John Paul II said that although the death penalty was permissible, he thought that the conditions which would allow for its execution were “very rare, if not practically non-existent” (Evangelium Vitae 56). But such a point of view is not binding on Catholics. Pope Francis’ revision does not mean that the Church now says that the death penalty is intrinsically wrong. Rather, the holy father is making a personal judgment about the matter. In one sense, Catholics have a duty to assent to this teaching, out of respect for the Supreme Pontiff’s authority. However, while a Catholic ought to assent to this teaching out of respect, he must assent to matters of dogma and doctrine out of obligation. Not assenting the application of this revised teaching regarding the death penalty may be sinful insofar as it is disrespectful to God because it disrespects the man He gave authority to govern His Church on earth. But not assenting to dogmas and doctrines of the Church would be sinful, even gravely sinful.
One may object to this line of reasoning, though, by saying that the pope could theoretically make the new Catechism read something to the effect of: “the Church now declares that the death penalty is intrinsically evil.” This hypothetical phrasing of the Catechism would indeed seem to constitute a doctrinal change and so undermine the Church’s authority. But firstly, we must be careful when forming hypotheticals, because they are de facto not grounded in reality. However, supposing this statement made its way into a new version of the Catechism, then this would not disprove the ordinary magisterium’s ability to teach infallibly in unison on the matters of faith and morals because there would not be unanimous consent among bishops regarding this change. If there were unanimous consent among bishops, or if the pope defined this ex cathedra, then there would be a problem. But Christ has revealed to us that such a thing will never happen, because the “gates of hell shall” never prevail against the Church (Mt 16:18).
Moreover, The Catechism of the Catholic Church is not an infallible document. Pope St. John Paul II first promulgated this Catechism in 1992, as a means of clarifying Church teaching and making it readily accessible to everyone around the world. Although the Catechism contains many infallible Church teachings, such as those on the Trinity, the Eucharist, the Resurrection, etc., it itself is not infallible.
Then there are disciplines, which apply to Catholic life. For example, Friday abstinence from meat, liturgical rites, fast and feast days, etc. are all disciplines, which the Church binds on believers by her God-given authority. It is not intrinsically wrong to eat meat on Fridays or intrinsically right to celebrate Christmas on December 25th, but the Church has the authority to make believers abide by these practices. These disciplines do, however, have theological backing. Christ was crucified on a Friday, so the Church has always observed Friday as a day of penance, Christ rose on a Sunday, so the Church has always observed Sunday as a feast day, etc. We see then, that the Church’s understanding of truth develops, but truth does not change. If a truth changed, it would not be true.
Perhaps surprisingly, one common justification for Protestantism is the theory of Development of Doctrine. Some Protestant groups will claim that doctrine has developed into a certain denomination or denominations of Protestantism. However, this claim misunderstands doctrinal development, because any denomination of Protestantism denies fundamental truths of the Catholic Faith (i.e. Papal Supremacy, Transubstantiation, Confession). The Pope does not stop being the temporal ruler of the Church. The Eucharist does not cease to be the Body and Blood of Christ.