Infallibility of the Church
The infallibility of the Church is the belief that the Holy Spirit preserves the Church from errors that would corrupt its essential doctrines. It is related to, but not the same as, the indefectibility of the Church, which is the belief that "the Church is indefectible, that is, she remains and will remain the Institution of Salvation, founded by Christ, until the end of the world."
Infallibility of the ecumenical councils
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 first seven general councils as genuinely ecumenical, while Roman Catholics accept twenty-one. Only a very few Protestants believe in the infallibility of ecumenical councils, but they usually restrict this 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.
While the Russian Orthodox Church does recognize the first seven ecumenical councils as valid, some Russian Orthodox[who?] theologians believe that the infallibility of these councils' statements derived from their acceptance by the faithful (and thus from the infallibility of all believers), and not from the acts of the councils themselves. This differs from the Greek Orthodox view, which accepts that an ecumenical council is itself infallible when pronouncing on a specific matter.
Roman Catholic Church
The Roman Catholic Church 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.
The magisterium (Latin: magister, "teacher") is the teaching office of the Roman Catholic Church. Roman 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), as well as of the ordinary and universal magisterium. Despite its name, the "ordinary and universal magisterium" falls under the infallible sacred magisterium, and in fact is the usual manifestation of the infallibility of the Church, the decrees of popes and councils being "extraordinary".
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.
Examples of infallible extraordinary Conciliar decrees include the Council of Trent's decree on justification, and Vatican I's definition of papal infallibility.
Examples of infallible teachings of the ordinary and universal magisterium are harder to point to, since these are not contained in any one specific document, but are the common teachings found among the Bishops dispersed through the world yet united with the pope. Pope John Paul II specifically clarified that the reservation of ordination to males is infallible under the infallibility of the ordinary and universal magisterium of the Church, without issuing a corresponding extraordinary papal definition. It has been suggested that Pope John Paul II did this to remind everyone that the ordinary and universal magisterium can also be infallible, and that an extraordinary definition is not necessary to make a teaching irrevocably binding and demanding of supernatural faith. In fact, the ordinary and universal magisterium is the usual manifestation of infallibility, the decrees of popes and councils being the extraordinary expression.
The document Pope John Paul II approved—signed by Cardinal Ratzinger, Prefect of the Congregation for the Doctrine of the Faith and later Pope Benedict XVI, and Cardinal Tarcisio Bertone—answers the question "Whether the teaching that the Church has no authority whatsoever to confer priestly ordination on women, which is presented in the Apostolic Letter Ordinatio Sacerdotalis to be held definitively, is to be understood as belonging to the deposit of faith" with "Affirmative." 
Also, another document signed by then-Cardinal Ratzinger and Cardinal Bertone says of the infallibility of Ordinatio Sacerdotalis:
A similar process can be observed in 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.
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. Such teachings are fallible and could possibly contain errors; they are subject to revisions or even, rarely, 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. Eventually, many fallible teachings progress to the point where they can be infallibly defined (such as when they become not only Ordinary, but Ordinary and Universal). Thus, some teachings move from the ordinary magisterium to the sacred magisterium.
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, however. 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, is more consonant with the tradition of the whole history of the Church, or how to reconcile them. 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 that are of the same level of authority, and being taught more recently does not necessarily give it more authority. For example, the different teachings of two bishops may be considered and judged by Catholics, and the fallible teachings of the current pope, for example, do not necessarily trump the equally authoritative fallible teaching of previous popes even when they disagree, especially if many of them taught something different. However, the fallible teachings must always be viewed in light of the infallible teachings of the Church.
All teachings of the sacred magisterium are considered infallible in Catholic theology. 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 in the public revelation of scripture and tradition. Rather, they demand supernatural faith as part of the faith in the Holy Spirit's guarantee of the authority and infallibility of the Church in discerning such matters. 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, or Mary's status as Mother of Christians.
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 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.
This doctrine is held by the Catholic Church. It was defined at the First Vatican Council in 1870, although belief in this doctrine long predated this council. The rejection of this doctrine is a common definitional element of the various Protestant denominations and of more recent break-away groups such as the Old Catholic Church.
Ordinary and universal magisterium
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.
Eastern Orthodox Church
Since the authority here claimed is associated with the doctrine of apostolic succession and is founded on sacred scripture and sacred tradition, it is not entirely foreign to the Orthodox Church. The Orthodox Church believes that the bishops are responsible for preserving the faith, the dogmatic truths and traditions. This does not equate to any of the bishops being individually infallible, but means that, in consensus, in combined agreement, they are charged with the universal faith. 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.
Tradition and 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
Consequences for ecumenism
The Catholic Church, the Eastern 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 this is one of the most divisive of issues between churches. This term unfortunately 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 firstly 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.
- Vatican I, Dei Filius ch. 3 ¶ 1, available at http://www.ewtn.com/library/councils/v1.htm#4. Vatican II, Lumen gentium § 25 ¶ 2, available at http://www.ewtn.com/library/councils/v2church.htm. 1983 Code of Canon Law 749 § 2, available at http://www.vatican.va/archive/ENG1104/__P2H.HTM.
- See, e.g. Lutheran-Orthodox Joint Commission, Seventh Meeting, The Ecumenical Councils, Common Statement, 1993, available at http://www.helsinki.fi/~risaarin/lutortjointtext.html#ecum ("We agree on the doctrine of God, the Holy Trinity, as formulated by the Ecumenical Councils of Nicaea and Constantinople and on the doctrine of the person of Christ as formulated by the first four Ecumenical Councils.").
- See The Conciliar Anglican, Ask An Anglican: The Ecumenical Councils, Aug. 3, 2011, available at http://conciliaranglican.com/2011/08/03/ask-an-anglican-the-ecumenical-councils/ ("While it is possible for a Council to err, it is so manifestly unlikely in the event of a truly Ecumenical Council that the conclusions of such a Council should be treated as final.").
- "The infallibility of the Church does not mean that the Church, in the assembly of the Fathers or in the expression of the Conscience of the Church, has already formally expressed all the truths of faith and norms. The infallibility of the Church is confined to the formulation of truths in question. This infallibility is not wholly a God-inspired energy which would affect the participants of the synod to such an extent that they would be inspired to pronounce all the truths at one time as a whole system of a Christian catechism. The Synod does not formulate a system of beliefs encompassing all Christian teachings and truths, but only endeavors to define the particular disputed truth which was misunderstood and misinterpreted. The Church of Christ and its divine nature, as set forth above, is the foundation upon which the Eastern Orthodox Church [sic.] continues to administer and nourish its faithful, thereby protecting its fundamental essentials." Rev. George Mastrantonis, of the Greek Orthodox Archdiocese of America.
- RESPONSUM AD PROPOSITUM DUBIUM, CONCERNING THE TEACHING CONTAINED IN “ORDINATIO SACERDOTALIS”. Published: 28 October 1995.
- DOCTRINAL COMMENTARY ON THE CONCLUDING FORMULA OF THE PROFESSIO FIDEI. EWTN. Retrieved: 23 March 2013
- Vatican I, Dei Filius ch. 3 ¶ 1 and Pastor Aeternus ch. 4 ¶ 5. Vatican II, Lumen gentium § 25 ¶ 3. 1983 Code of Canon Law 749 § 1.
- Yes, we know that popes are not perfect.. Answering Protestants. Published: 21 February 2013.
- Does papal infallibility mean the pope is perfect or inerrant?. Catholic Answers. Retrieved: 23 March 2013.