The original saying by Saint Cyprian of Carthage (3rd century AD) is found his Letter LXXII, Ad Jubajanum de haereticis baptizandis, and in Latin reads: "Salus extra ecclesiam non est".[5]

The belief has been echoed by Fathers and Doctors of the Church, and various saints:[1]

Saint Irenaeus (died A.D. 202):
“[The Church] is the entrance to life; all others are thieves and robbers. On this account we are bound to avoid them… We hear it declared of the unbelieving and the blinded of this world that they shall not inherit the world of life which is to come… Resist them in defense of the only true and life giving faith, which the Church has received from the Apostles and imparted to her sons.” (Against Heresies , Book III)
Origen (died A.D. 254):
“Let no man deceive himself. Outside this house, that is, outside the Church no one is saved.” (In Iesu Nave homiliae )
Saint Cyprian (died A.D. 258):
“He who has turned his back on the Church of Christ shall not come to the rewards of Christ; he is an alien, a worldling, an enemy. You cannot have God for your Father if you have not the Church for your mother. Our Lord warns us when He says: `he that is not with Me is against Me, and he that gathereth not with Me scattereth.’ Whosoever breaks the peace and harmony of Christ acts against Christ; whoever gathers elsewhere than in the Church scatters the Church of Christ.” (Unity of the Catholic Church )
“He who does not hold this unity, does not hold the law of God, does not hold the faith of the Father and the Son, does not hold life and salvation.” (Patrologiae Cursus Completus: Latina , Father Migne)
“Nay, though they should suffer death for the confession of the Name, the guilt of such men is not removed even by their blood…No martyr can he be who is not in the Church.” (Ancient Christian Writers )
Bishop Firmilean (died A.D. 269):
“What is the greatness of his error, and what the depth of his blindness, who says that remission of sins can be granted in the synagogues of heretics, and does not abide on the foundation of the one Church.” (Anti-Nicene Fathers )
Lactantius (died A.D. 310):
“It is the Catholic Church alone which retains true worship. This is the fountain of truth, this is the abode of the Faith, this is the temple of God; into which if anyone shall not enter, or from which if anyone shall go out, he is a stranger to the hope of life and eternal salvation.” (The Divine Institutes )
Saint Cyril of Jerusalem (died A.D. 386):
“Abhor all heretics…heed not their fair speaking or their mock humility; for they are serpents, a `brood of vipers.’ Remember that, when Judas said `Hail Rabbi,’ the salutation was an act of betrayal. Do not be deceived by the kiss but beware of the venom. Abhor such men, therefore, and shun the blasphemers of the Holy Spirit, for whom there is no pardon. For what fellowship have you with men without hope. Let us confidently say to God regarding all heretics, `Did I not hate, O Lord, those who hated Thee, and did I not pine away because of Your enemies?’ For there is an enmity that is laudable, as it is written, `I will put enmity between you and the woman, between your seed and her seed.’ Friendship with the serpent produces enmity with God, and death. Let us shun those from whom God turns away.” (The Fathers of the Church )
Saint Ambrose (died A.D. 397):
“Where Peter is therefore, there is the Church. Where the Church is there is not death but life eternal. …Although many call themselves Christians, they usurp the name and do not have the reward.” (The Fathers of the Church )
Bishop Niceta of Remesiana (died A.D. 415):
“He is the Way along which we journey to our salvation; the Truth, because He rejects what is false; the Life, because He destroys death. …All who from the beginning of the world were, or are, or will be justified – whether Patriarchs, like Abraham, Isaac and Jacob, or Prophets, whether Apostles or martyrs, or any others – make up one Church, because they are made holy by one faith and way of life, stamped with one Spirit, made into one Body whose Head, as we are told, is Christ. I go further. The angels and virtues and powers in heaven are co-members in this one Church, for, as the Apostle teaches us, in Christ `all things whether on the earth or in the heavens have been reconciled.’ You must believe, therefore, that in this one Church you are gathered into the Communion of Saints. You must know that this is the one Catholic Church established throughout the world, and with it you must remain in unshaken communion. There are, indeed, other so called `churches’ with which you can have no communion. …These `churches’ cease to be holy, because they were deceived by the doctrines of the devil to believe and behave differently from what Christ commanded and from the tradition of the Apostles.” (The Fathers of the Church )
Saint Jerome (died A.D. 420):
“As I follow no leader save Christ, so I communicate with none but your blessedness, that is, with the Chair of Peter. For this, I know, is the rock on which the Church is built. …This is the ark of Noah, and he who is not found in it shall perish when the flood prevails. …And as for heretics, I have never spared them; on the contrary, I have seen to it in every possible way that the Church’s enemies are also my enemies.” (Manual of Patrology and History of Theology )
Saint Augustine (died A.D. 430):
“No man can find salvation except in the Catholic Church. Outside the Catholic Church one can have everything except salvation. One can have honor, one can have the sacraments, one can sing alleluia, one can answer amen, one can have faith in the name of the Father and of the Son and of the Holy Ghost, and preach it too, but never can one find salvation except in the Catholic Church.” (Sermo ad Caesariensis Ecclesia plebem )
Saint Fulgentius (died A.D. 533):
“Most firmly hold and never doubt that not only pagans, but also all Jews, all heretics, and all schismatics who finish this life outside of the Catholic Church, will go into the eternal fire prepared for the devil and his angels.” (Enchiridion Patristicum )
Saint Bede the Venerable (died A.D. 735):
“Just as all within the ark were saved and all outside of it were carried away when the flood came, so when all who are pre-ordained to eternal life have entered the Church, the end of the world will come and all will perish who are found outside.” (Hexaemeron )
Saint Thomas Aquinas (died A.D. 1274):
“There is no entering into salvation outside the Church, just as in the time of the deluge there was none outside the ark, which denotes the Church.” (Summa Theologiae )
Saint Peter Canisius (died A.D. 1597):
“Outside of this communion – as outside of the ark of Noah – there is absolutely no salvation for mortals: not for Jews or pagans who never received the faith of the Church, nor for heretics who, having received it, corrupted it; neither for the excommunicated or those who for any other serious cause deserve to be put away and separated from the body of the Church like pernicious members…for the rule of Cyprian and Augustine is certain: he will not have God for his Father who would not have the Church for his mother.” (Catechismi Latini et Germanici )
Saint Robert Bellarmine (died A.D. 1621):
“Outside the Church there is no salvation…therefore in the symbol [Apostles Creed] we join together the Church with the remission of sins: `I believe in the Holy Catholic Church, the communion of Saints, the forgiveness of sins’…For this reason the Church is compared with the ark of Noah, because just as during the deluge, everyone perished who was not in the ark, so now those perish who are not in the Church.” (De Sacramento Baptismi )
As well as Councils and various Popes:

Fourth Lateran Council (1215): "There is but one universal Church of the faithful, outside which no one at all is saved."
Pope Boniface VIII, Bull Unam sanctam (1302): "We are compelled in virtue of our faith to believe and maintain that there is only one holy Catholic Church, and that one is apostolic. This we firmly believe and profess without qualification. Outside this Church there is no salvation and no remission of sins, the Spouse in the Canticle proclaiming: 'One is my dove, my perfect one. One is she of her mother, the chosen of her that bore her' (Canticle of Canticles 6:8); which represents the one mystical body whose head is Christ, of Christ indeed, as God. And in this, 'one Lord, one faith, one baptism' (Ephesians 4:5). Certainly Noah had one ark at the time of the flood, prefiguring one Church which perfect to one cubit having one ruler and guide, namely Noah, outside of which we read all living things were destroyed… We declare, say, define, and pronounce that it is absolutely necessary for the salvation of every human creature to be subject to the Roman Pontiff."
Pope Eugene IV, Cantate Domino (1441): "The most Holy Roman Church firmly believes, professes and preaches that none of those existing outside the Catholic Church, not only pagans, but also Jews and heretics and schismatics, can have a share in life eternal; but that they will go into the "eternal fire which was prepared for the devil and his angels" (Matthew 25:41), unless before death they are joined with Her; and that so important is the unity of this ecclesiastical body that only those remaining within this unity can profit by the sacraments of the Church unto salvation, and they alone can receive an eternal recompense for their fasts, their almsgivings, their other works of Christian piety and the duties of a Christian soldier. No one, let his almsgiving be as great as it may, no one, even if he pour out his blood for the Name of Christ, can be saved, unless he remain within the bosom and the unity of the Catholic Church."
Pope Boniface I, Epistle 14.1: "It is clear that this Roman Church is to all churches throughout the world as the head is to the members, and that whoever separates himself from it becomes an exile from the Christian religion, since he ceases to belong to its fellowship."
Pope Pelagius II (578-590): "Consider the fact that whoever has not been in the peace and unity of the Church cannot have the Lord… Although given over to flames and fires, they burn, or, thrown to wild beasts, they lay down their lives, there will not be (for them) that crown of faith but the punishment of faithlessness… Such a one can be slain, he cannot be crowned… [If] slain outside the Church, he cannot attain the rewards of the Church" (Denzinger, 469).
Pope Saint Gregory the Great (590-604), Moralia: "Now the holy Church universal proclaims that God cannot be truly worshipped saving within herself, asserting that all they that are without her shall never be saved."
Pope Sylvester II, Profession of Faith, June AD 991: "I believe that in Baptism all sins are forgiven, that one which was committed originally as much as those which are voluntarily committed, and I profess that outside the Catholic Church no one is saved."
Pope Innocent III (1198–1216), Profession of Faith prescribed for the Waldensians: "With our hearts we believe and with our lips we confess but one Church, not that of the heretics, but the Holy Roman Catholic and Apostolic Church, outside which we believe that no one is saved" (Denzinger 792).
Pope Clement VI, Letter Super quibusdam (to Consolator the Catholicosof Armenia), September 20, 1351: "In the second place, we ask whether you and the Armenians obedient to you believe that no man of the wayfarers outside of the faith of this Church, and outside the obedience of the Pope of Rome, can finally be saved… In the ninth place, if you have believed and do believe that all who have raised themselves against the faith of the Roman Church and have died in final impenitence have been damned and have descended to the eternal punishments of hell."
Pope Leo XII (1823–1829), Encyclical Ubi primum: "It is impossible for the most true God, who is Truth Itself, the best, the wisest Provider, and rewarder of good men, to approve all sects who profess false teachings which are often inconsistent with one another and contradictory, and to confer eternal rewards on their members. For we have a surer word of the prophet, and in writing to you We speak wisdom among the perfect; not the wisdom of this world but the wisdom of God in a mystery. By it we are taught, and by divine faith we hold, one Lord, one faith, one baptism, and that no other name under heaven is given to men except the name of Jesus Christ of Nazareth in which we must be saved. This is why we profess that there is no salvation outside the Church… For the Church is the pillar and ground of the truth. With reference to those words Augustine says: 'If any man be outside the Church he will be excluded from the number of sons, and will not have God for Father since he has not the Church for mother.'"
Pope Gregory XVI (1831–1846), Encyclical Summo jugiter studio (on mixed marriages), 5-6, May 27, 1832: "You know how zealously Our predecessors taught that very article of faith which these dare to deny, namely the necessity of the Catholic faith and of unity for salvation. The words of that celebrated disciple of the Apostles, martyred Saint Ignatius, in his letter to the Philadelphians are relevant to this matter: 'Be not deceived, my brother; if anyone follows a schismatic, he will not attain the inheritance of the kingdom of God.' Moreover, Saint Augustine and the other African bishops who met in the Council of Cirta in the year 412 explained the same thing at greater length: 'Whoever has separated himself from the Catholic Church, no matter how laudably he lives, will not have eternal life, but has earned the anger of God because of this one crime: that he abandoned his union with Christ' (Epsitle 141). Omitting other appropriate passages which are almost numberless in the writings of the Fathers, We shall praise Saint Gregory the Great, who expressly testifies that this is indeed the teaching of the Catholic Church. He says: 'The holy universal Church teaches that it is not possible to worship God truly except in her and asserts that all who are outside of her will not be saved' (Moral. in Job, 16.5). Official acts of the Church proclaim the same dogma. Thus, in the decree on faith which Innocent III published with the synod of the Lateran IV, these things are written: 'There is one universal Church of the faithful outside of which no one at all is saved.' Finally, the same dogma is expressly mentioned in the profession of faith proposed by the Apostolic See, not only that which all Latin churches use (Creed of the Council of Trent), but also that which the Greek Orthodox Church uses (cf. Gregory XIII, Profession 'Sanctissimus') and that which other Eastern Catholics use (cf. Benedict XIV, Profession 'Nuper ad Nos')… We are so concerned about this serious and well known dogma, which has been attacked with such remarkable audacity, that We could not restrain Our pen from reinforcing this truth with many testimonies."
Pope Pius IX (1846–1878), Allocution Singulari quadam, December 9, 1854: "Not without sorrow we have learned that another error, no less destructive, has taken possession of some parts of the Catholic world, and has taken up its abode in the souls of many Catholics who think that one should have good hope of the eternal salvation of all those who have never lived in the true Church of Christ. Therefore, they are wont to ask very often what will be the lot and condition of those who have not submitted in any way to the Catholic faith, and, by bringing forward most vain reasons, they make a response favorable to their false opinion. Far be it from Us, Venerable Brethren, to presume on the limits of the divine mercy which is infinite; far from Us, to wish to scrutinize the hidden counsel and "judgements of God" which are "a great abyss" (Ps. 35.7) and cannot be penetrated by human thought. But, as is Our Apostolic Duty, we wish your episcopal solicitude and vigilance to be aroused, so that you will strive as much as you can to drive form the mind of men that impious and equally fatal opinion, namely, that the way of eternal salvation can be found in any religion whatsoever. May you demonstrate with skill and learning in which you excel, to the people entrusted to your care that the dogmas of the Catholic faith are in no wise opposed to divine mercy and justice.
"For, it must be held by faith that outside the Apostolic Roman Church, no one can be saved; that this is the only ark of salvation; that he who shall not have entered therein will perish in the flood; but, on the other hand, it is necessary to hold for certain that they who labor in ignorance of the true religion, if this ignorance is invincible, will not be held guilty of this in the eyes of God. Now, in truth, who would arrogate so much to himself as to mark the limits of such an ignorance, because of the nature and variety of peoples, regions, innate dispositions, and of so many other things? For, in truth, when released from these corporeal chains 'we shall see God as He is' (1 John 3.2), we shall understand perfectly by how close and beautiful a bond divine mercy and justice are united; but as long as we are on earth, weighed down by this mortal mass which blunts the soul, let us hold most firmly that, in accordance with Catholic teaching, there is "one God, one faith, one baptism" (Eph. 4.5); it is unlawful to proceed further in inquiry.
"But, just as the way of charity demands, let us pour forth continual prayers that all nations everywhere may be converted to Christ; and let us be devoted to the common salvation of men in proportion to our strength, 'for the hand of the Lord is not shortened' (Isa. 9.1) and the gifts of heavenly grace will not be wanting to those who sincerely wish and ask to be refreshed by this light."[6]
Pope Pius IX (1846–1878), Encyclical Singulari quidem March 17, 1856): "Teach that just as there is only one God, one Christ, one Holy Spirit, so there is also only one truth which is divinely revealed. There is only one divine faith which is the beginning of salvation for mankind and the basis of all justification, the faith by which the just person lives and without which it is impossible to please God and come to the community of His children (Romans 1; Hebrews 11; Council of Trent, Session 6, Chapter 8). There is only one true, holy, Catholic Church, which is the Apostolic Roman Church. There is only one See founded on Peter by the word of the Lord (St. Cyprian, Epistle 43), outside of which we cannot find either true faith or eternal salvation. He who does not have the Church for a mother cannot have God for a father, and whoever abandons the See of Peter on which the Church is established trusts falsely that he is in the Church (ibid, On the Unity of the Catholic Church). ... Outside of the Church, nobody can hope for life or salvation unless he is excused through ignorance beyond his control."[7]
Pope Pius IX (1846–1878), Encyclical Quanto conficiamur moerore, August 10, 1863: "And here, beloved Sons and Venerable Brothers, We should mention again and censure a very grave error in which some Catholics are unhappily engaged, who believe that men living in error, and separated from the true faith and from Catholic unity, can attain eternal life. Indeed, this is certainly quite contrary to Catholic teaching. It is known to Us and to you that they who labor in invincible ignorance of our most holy religion and who, zealously keeping the natural law and its precepts engraved in the hearts of all by God, and being ready to obey God, live an honest and upright life, can, by the operating power of divine light and grace, attain eternal life, since God who clearly beholds, searches, and knows the minds, souls, thoughts, and habits of all men, because of His great goodness and mercy, will by no means suffer anyone to be punished with eternal torment who has not the guilt of deliberate sin. But, the Catholic dogma that no one can be saved outside the Catholic Church is well-known; and also that those who are obstinate toward the authority and definitions of the same Church, and who persistently separate themselves from the unity of the Church, and from the Roman Pontiff, the successor of Peter, to whom 'the guardianship of the vine has been entrusted by the Savior,' (Council of Chalcedon, Letter to Pope Leo I) cannot obtain eternal salvation. The words of Christ are clear enough: 'And if he will not hear the Church, let him be to thee as the heathen and publican' (Matthew 18:17); 'He that heareth you, heareth Me; and he that dispeth you, despiseth Me; and he that dispiseth Me, despiseth Him that sent Me' (Luke 10:16); 'He that believeth not shall be condemned' (Mark 16:16); 'He that doth not believe, is already judged' (John 3:18); 'He that is not with Me, is against Me; and he that gathereth not with Me, scattereth' (Luke 11:23). The Apostle Paul says that such persons are 'perverted and self-condemned' (Titus 3:11); the Prince of the Apostles calls the 'false prophets… who shall bring in sects of perdition, and deny the Lord who bought them: bringing upon themselves swift destruction' (2 Peter 2:1)."[8]
Pope Pius IX The Syllabus of Errors, attached to Encyclical Quanta cura, 1864: [The following are prescribed errors:] "16. Men can, in the cult of any religion, find the way of eternal salvation and attain eternal salvation. - Encyclical Qui pluribus, November 9, 1846. "17. One ought to at least have good hope for the eternal salvation of all those who in no way dwell in the true Church of Christ. - Encyclical Quanto conficiamur moerore, August 10, 1863, etc."
Pope Leo XIII (1878–1903), Encyclical Annum ingressi sumus: "This is our last lesson to you; receive it, engrave it in your minds, all of you: by God's commandment salvation is to be found nowhere but in the Church." idem, Encyclical Sapientiae christianae: "He scatters and gathers not who gathers not with the Church and with Jesus Christ, and all who fight not jointly with Him and with the Church are in very truth contending against God."
Pope St. Pius X (1903–1914), Encyclical Jucunda sane: "It is our duty to recall to everyone great and small, as the Holy Pontiff Gregory did in ages past, the absolute necessity which is ours, to have recourse to this Church to effect our eternal salvation."
Pope Benedict XV (1914–1922), Encyclical Ad Beatissimi Apostolorum: "Such is the nature of the Catholic faith that it does not admit of more or less, but must be held as a whole, or as a whole rejected: This is the Catholic faith, which unless a man believe faithfully and firmly, he cannot be saved."
Pope Pius XI (1922–1939), Encyclical Mortalium Animos: "The Catholic Church alone is keeping the true worship. This is the font of truth, this is the house of faith, this is the temple of God; if any man enter not here, or if any man go forth from it, he is a stranger to the hope of life and salvation… Furthermore, in this one Church of Christ, no man can be or remain who does not accept, recognize and obey the authority and supremacy of Peter and his legitimate successors."
Pope Pius XII (1939–1958), Encyclical Humani Generis, August 12, 1950: "Some reduce to a meaningless formula the necessity of belonging to the true Church in order to gain eternal salvation."
Pope Pius XII (1939–1958), Allocution to the Gregorian University (17 October 1953): "By divine mandate the interpreter and guardian of the Scriptures, and the depository of Sacred Tradition living within her, the Church alone is the entrance to salvation: She alone, by herself, and under the protection and guidance of the Holy Spirit, is the source of truth."
Second Vatican Council, Dogmatic Constitution Lumen gentium, 14: "They could not be saved who, knowing that the Catholic Church was founded as necessary by God through Christ, would refuse either to enter it, or to remain in it."
Second Vatican Council, Dogmatic Constitution Lumen gentium, 16: ". . .Nor is God far distant from those who in shadows and images seek the unknown God, for it is He who gives to all men life and breath and all things, and as Saviour wills that all men be saved. Those also can attain to salvation who through no fault of their own do not know the Gospel of Christ or His Church, yet sincerely seek God and moved by grace strive by their deeds to do His will as it is known to them through the dictates of conscience. Nor does Divine Providence deny the helps necessary for salvation to those who, without blame on their part, have not yet arrived at an explicit knowledge of God and with His grace strive to live a good life. . .But often men, deceived by the Evil One, have become vain in their reasonings and have exchanged the truth of God for a lie, serving the creature rather than the Creator. Or some there are who, living and dying in this world without God, are exposed to final despair. . ."