The infallibility of the Church is the belief that the Holy Spirit preserves the Christian Church from errors that would contradict its essential doctrines. It is related to, but not the same as, indefectible, that is, "she remains and will remain the Institution of Salvation, founded by Christ, until the end of the world." The doctrine of infallibility is premised on the authority Jesus granted to the apostles to "bind and loose" (Mat 18:18; John 20:23) and particularly the promises to Peter (Mat 16:16–20; Luke 22:32) in regard to papal infallibility.
The doctrine of the infallibility of ecumenical councils states that solemn definitions of ecumenical councils, approved by the Pope, which concern faith or morals, and to which the whole Church must adhere, are infallible. Such decrees are often labeled as canons, and they often have an attached anathema, a penalty of excommunication, against those who refuse to believe the teaching. The doctrine does not claim that every aspect of every ecumenical council is infallible.
The Roman Catholic Church holds this doctrine, as do most or all Eastern Orthodox theologians. However, the Orthodox churches accept only the Seven Ecumenical Councils from Nicaea I to Nicaea II as genuinely ecumenical, while Roman Catholics accept twenty-one. Only a very few Protestants believe in the infallibility of ecumenical councils, and these usually restrict infallibility to the Christological statements of the first seven councils. Lutheran Christians recognize the first four councils, whereas most High Church Anglicans accept all seven as persuasive but not infallible.
A popular view among Orthodox Christians, especially Greek Orthodox and Churches that fall within the Ecumenical Patriarchate, is that an ecumenical council is itself infallible when pronouncing on a specific matter such as Christology, whereas others hold that a council can be considered of full ecumenical authority only once its declarations have been embraced by the faithful, an opinion more common among the Slavic Churches, such as the Russian Orthodox.
Catholicism teaches that Jesus Christ, "the Word made Flesh" (John 1:14), is the source of divine revelation. The Second Vatican Council states, "For this reason Jesus perfected revelation by fulfilling it through His whole work of making Himself present and manifesting Himself: through His words and deeds, His signs and wonders, but especially through His death and glorious resurrection from the dead and final sending of the Spirit of truth." (Dei verbum, 4). The content of Christ's divine revelation is called the deposit of faith, and is contained in both sacred scripture and sacred tradition, not as two sources but as a single source.
The magisterium (Latin: magister, "teacher") is the teaching office of the Catholic Church. Catholic theology divides the functions of the teaching office into two categories: the infallible sacred magisterium and the fallible ordinary magisterium. The infallible sacred magisterium includes the extraordinary declarations of the pope speaking ex cathedra and of ecumenical councils (traditionally expressed in conciliar creeds, canons, and decrees). Examples of infallible extraordinary papal definitions (and, hence, of teachings of the sacred magisterium) are Pope Pius IX's definition of the Immaculate Conception of Mary, and Pope Pius XII's definition of the Assumption of Mary. Before these definitions both sovereign pontiffs asked the bishops throughout the world whether these truths were indeed held by the faithful. Nowhere is it said that the Pope's charism involves special revelations, and the Pope must ascertain whether a belief is universally maintained before speaking ex cathedra on it. The above two instances of infallible definition outside an ecumenical council are the only two that can be cited in the history of the Catholic church.
A document signed by then-Cardinal Ratzinger and Cardinal Bertone speaks of
... the more recent teaching regarding the doctrine that priestly ordination is reserved only to men. The Supreme Pontiff, while not wishing to proceed to a dogmatic definition, intended to reaffirm that this doctrine is to be held definitively, since, founded on the written Word of God, constantly preserved and applied in the Tradition of the Church, it has been set forth infallibly by the ordinary and universal Magisterium. As the prior example illustrates, this does not foreclose the possibility that, in the future, the consciousness of the Church might progress to the point where this teaching could be defined as a doctrine to be believed as divinely revealed.
Notable here is the confirmation that the sensus fidelium is critical in determining whether a doctrine can be called infallible teaching.
Of the ordinary magisterium, the Second Vatican Council said: "Bishops, teaching in communion with the Roman Pontiff, are to be respected by all as witnesses to divine and Catholic truth. 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." The ordinary magisterium includes the potentially fallible teachings of the pope and ecumenical Councils (i.e., not given ex cathedra) and, more commonly, of individual Bishops or groups of Bishops as taken separately from the whole College of Bishops. Such teachings are fallible and could possibly contain errors; they are subject to revisions or revocation. In the case of the teachings of individual bishops to their diocese, there can of course even be disagreement among the individual bishops on such issues. However, these potentially fallible teachings are necessary to contribute to the development of doctrine.
Example of ordinary magisterium includes the social teachings of recent popes or theological opinions that the Popes or bishops make public. Catholics are not free to merely dismiss such teachings. The Church demands a "submission of the intellect and will" to them, even if not supernatural faith. However, this is to varying degrees depending on a variety of things, especially when teachers disagree. Catholics must respectfully hear all opinions from equal authorities and judge which is best, makes more sense, and is more consonant with the tradition of the whole history of the Church. However, the use of a higher level of authority trumps past disagreement—for example, if a pope condemns the teaching of a bishop (even if both the condemnation and the teaching are fallible), or if an infallible teaching disagrees with a past fallible teaching. Catholics are free to weigh a variety of factors, however, in judging divergent opinions. In the end all must follow their own, well-formed conscience.
Infallible teachings can be divided into two categories of precedence. The highest are called de fide credenda teachings, that is to say teachings defined as explicitly and specifically revealed in the deposit of faith: "Wherefore, by divine and Catholic faith all those things are to be believed which are contained in the word of God as found in Scripture and Tradition, and which are proposed by the Church as matters to be believed as divinely revealed, whether by her solemn judgment or in her ordinary and universal Magisterium." (First Vatican Council, Dei Filius 8.) The other category are called de fide tenenda teachings. These are equally infallible but are proposed not as being explicitly in the deposit of faith, but nevertheless implied by it or intrinsically connected to it logically or historically. These too demand supernatural faith, but not specifically in themselves on the authority of the Word of God. Further discernment may lead to the conclusion that a de fide tenenda teaching is not merely implied by the deposit of faith, but explicitly contained and thus it may advance to de fide credenda status.
Both extraordinary definitions and the universal magisterium may teach de fide credenda or de fide tenenda teachings. An example of de fide credenda teachings taught by extraordinary definition are the Christological teachings of the early ecumenical councils or the Marian dogmas of the Immaculate Conception and Assumption taught by the popes.
An example of de fide credenda teachings taught by infallible ordinary and universal magisterium include the immorality of directly taking an innocent human life.
Examples of de fide tenenda teachings taught by extraordinary definition include the canonizations of saints and Pope Leo XIII's declaration of Anglican orders as null and void (so-called "dogmatic facts"). Neither of these could advance to de fide credenda status as they are contingent on historical facts. However, certain teachings on grace and justification from the Council of Trent, currently regarded as infallible but only de fide tenenda due to disagreement about whether they are explicitly contained in the deposit of faith or merely logically implied, could someday advance to de fide credenda status either through extraordinary definition or through the consensus of the universal magisterium.
An opinion from a former member of the Congregation For the Doctrine of the Faith, Ratzinger holds Examples of de fide tenenda teachings taught by infallible ordinary and universal magisterium include the validity of papal elections, earlier non-papal canonizations now universally accepted (of St. Agnes, for example), or the immorality of pornography. However, none of these could advance to de fide credenda status as they are contingent on historical facts or developments, as for example pornography is condemned, and infallibly so, but is likely not included specifically in the deposit of faith (there was no such concept at the time), but is nevertheless an infallibly discerned implication of the more general revealed teachings on human sexuality and chastity. However, certain teachings taught in such a manner may someday advance to de fide credenda status, either through extraordinary definition or the consensus of the ordinary universal magisterium. As, for example, the teaching on papal infallibility was infallibly taught for a long time de fide tenenda by the universal magisterium, but not de fide credenda until the extraordinary definition at Vatican I, because there was disagreement on whether it was a specifically revealed truth from the deposit of faith or merely the logical implication of other things in the deposit of faith (as, for example, the authority of Saint Peter in the college of apostles, the constitution of the Church, her unity, her episcopal structure, etc.)
The doctrine of papal infallibility states that when the pope teaches ex cathedra his teachings are infallible and irreformable. Such infallible papal decrees must be made by the pope, in his role as leader of the whole Church, and they must be definitive decisions on matters of faith and morals which are binding on the whole Church. An infallible decree by a pope is often referred to as an ex cathedra statement. This type of infallibility falls under the authority of the sacred magisterium.
The doctrine of papal infallibility was formally defined at the First Vatican Council in 1870, although belief in this doctrine long predated this council and was premised on the promises of Jesus to Peter, promises to Peter (Mat 16:16-20; Luke 22:32). The encyclicals of the First Vatican Council, however were rejected by a small minority of bishops who separated themselves from union with the Bishop or Rome to form, or preserve, the Old Catholic Church.
The ordinary and universal episcopal magisterium is considered infallible as it relates to a teaching concerning a matter of faith and morals that all the bishops of the Church (including the Pope) universally hold as definitive and only as such therefore needing to be accepted by all the faithful. This aspect of infallibility only applies to teachings about faith and morals as opposed to customs and prudential practices. Additionally, the ordinary and universal episcopal magisterium applies to a teaching to be held definitively by all the bishops at any given moment in history. Such teachings are extremely hard to prove. Thus, even if a teaching on a matter of faith and morals is out of favor among the bishops of a later date, once it has been held definitively by all bishops to be accepted by the faithful as infallible, then it is considered infallible and unchangeably true. However, Bishops all agreeing to a teaching to be held inconclusively are not teaching it to be definitive. It must be clearly established to be definitive for all time. This was attempted to be thoroughly done and documented in the case of several statements contained in Evangelium vitae.
The Eastern Orthodox Churches also believe in apostolic succession through which Christ promised to preserve the Church from teaching error. This grace and authority, however, does not make any of the bishops being individually infallible, however, but rather means that, in consensus, in combined agreement, they are charged with preserving the universal faith from error. Thus the Orthodox Church does not use the term "infallible" to discuss the works of any bishop or council. Orthodox Christians regard the concept of infallibility to be uniquely Western and therefore avoid the use of defining or terming even Ecumenical Councils as infallible. Ecumenical Councils are felt, in the East, to be a continuation of the apostolic faith, and that the apostolic faith does not change. However, it also believes that not every council that proclaims itself ecumenical is so in fact. The Orthodox would also not accept the infallibility of the ordinary and universal magisterium.
The Church of England claimed this type of authority over the people of England, but the idea is no longer popular within the church, owing to a lack of commonly-accepted traditions and to disputes as to some peripheral doctrines. However, Anglicanism holds to a unique ecclesiology: in the Anglican view, the ancient and historic churches (such as the Anglican, Roman Catholic, Orthodox and Oriental churches) that maintained apostolic succession, belief, and practice are all branches of the Universal Church and there will always be a section of this tripartite church which will not fall into major heresy.
A common defining belief of Protestant denominations is a rejection of the idea that any church leaders (popes, bishops, priests, or elders) are preserved from teaching error, or conversely are infallible in their interpretations of Scripture, and that believers are not therefore obligated to accept "infallible" doctrines which they, in good conscience, do not believe are supported by Scripture.
Catholics, Orthodox, and some Anglicans believe that divine revelation (the one "Word of God") is contained both in the words of God in sacred scripture and in the deeds of God in sacred tradition. Everything asserted as true by either scripture or tradition is true and infallible.
This plan of revelation is realized by deeds and words having an inner unity: the deeds wrought by God in the history of salvation manifest and confirm the teaching and realities signified by the words, while the words proclaim the deeds and clarify the mystery contained in them. By this revelation then, the deepest truth about God and the salvation of man shines out for our sake in Christ, who is both the mediator and the fullness of all revelation.— Second Vatican Council, Dei verbum, n. 2
Yves Congar, who thought Catholics could acknowledge a substantial element of truth in sola scriptura, wrote that "we can admit sola scriptura in the sense of a material sufficiency of canonical Scripture. This means that Scripture contains, in one way or another, all truths necessary for salvation." This has led to the tenable position of the "two modes" theory.
In his book, James F. Keenan reports studies by some academics. A study by Bernard Hoose states that claims to a continuous teaching by the Church on matters of sexuality, life and death, and crime and punishment are "simply not true." After examining seven medieval texts about homosexuality, Mark Jordan argues that, "far from being consistent, any attempt to make a connection among the texts proved impossible." He calls the tradition's teaching of the Church "incoherent". Karl-Wilhelm Merks considers that tradition itself is "not the truth guarantor of any particular teaching." Keenan, however, says that studies of "manualists" such as John T. Noonan Jr. has demonstrated that, "despite claims to the contrary, manualists were co-operators in the necessary historical development of the moral tradition." Noonan, according to Keenan, has provided a new way of viewing at "areas where the Church not only changed, but shamefully did not."
The Roman Catholic, Eastern Orthodox, and Oriental Orthodox Churches, and the various Protestant denominations are divided by their different views on infallibility. The ecumenical movement, which hopes to reunify all of Christianity, has found that the papacy is one of the most divisive of issues between churches. Infallibility has often been misunderstood by most Christian denominations. Infallibility cannot be understood properly unless a sound comprehension of the administration and theology of each Christian group has first been understood. For example, many Protestants and Eastern Orthodox believers have the belief that papal infallibility refers to papal impeccability (meaning that the pope cannot sin). This, however, is not the teaching of papal infallibility.