The Catholic Church was instituted by Jesus Christ so that men might be forgiven their sins and so that they might participate in the Life of the Holy Trinity forever. The saving power of Jesus Christ’s Passion and Resurrection is made present and active on earth through Her. He is Her Head, She is His Body. He is Her Groom, She is His Bride. Providence has decreed that He is not present without Her—wherever Jesus Christ is, there She must be. St. Cyprian states the doctrine emphatically: “He cannot have God for his Father who does not have the Church for his Mother.”
Commonly held by Catholics before the 1960’s, the above doctrine, I am sorry to admit, is no longer openly proclaimed by many Catholics. Many priests, bishops, and cardinals would lead us to believe that the Church is only one of many institutions, communities, religions, or denominations whereby men might escape damnation (if they believe in such a thing these days) and enter into the Life of the Holy Trinity. Back in 2001 Cardinal Walter Kasper openly rejected the term “conversion” as it implied that the Catholic Church was necessary for salvation: “Today we no longer understand ecumenism in the sense of a return, by which the others would ‘be converted’ and return to being ‘catholics.’ This was expressly abandoned by Vatican II.” For example, says the Cardinal, the Church does not need to evangelize those who adhere to Judaism because they can be saved apart from the Church: “Therefore there does not exist any Catholic missionary organization for Jews. There is dialogue with Jews; no mission in this proper sense of the word towards them.”  Cardinal Kasper reasons that the Jews (and other non-Catholics) have their own thing going, why should they be concerned with the Crucified Lord and his Bride? The Catholic Church is only one way (the best way?) to have a relationship with God. Plus, we must seek unity above all else. Better to sacrifice the uniqueness of the Church on the altar of irenic ecumenism, he reasons, than to compromise our friendly relations with other Christians and non-Christians.
Your Eminence, Jesus had some rather harsh things to say about those shepherds who scandalize His little ones--something about millstones. 
Sacrificing the Church’s unique, salvific role runs squarely against the unanimous teachings of the early Church Fathers and the constant teaching of the Magisterium. The Church Fathers often compared the Church to the ark of Noah: just as no person could be saved from the floodwaters apart from the ark, so men could not escape damnation apart from the Church. St. Fulgence of Ruspe and St. Augustine of Hippo  would not have tolerated this false ecumenism promoted by Cardinal Kasper; St. Ignatius of Antioch  and St. Irenaeus of Lyons  devoted much of their polemics against those sects who sought salvation apart from the Church. St. Cyril of Jerusalem  and St. Jerome  insisted that there is no salvation apart from the Catholic Church. The very blood of the early Martyrs sealed their testimonies. Ecumenical councils and popes, ancient and modern (including Vatican II, your Eminence)  insisted on the Church’s unique and indispensable mediation for the salvation of all men--even those who might be saved in other religions. 
It is imperative that our rhetoric and dispositions once again conform to this ancient teaching of the Church. We must insist that those who have not sworn allegiance to the successor of Peter are only saved through the Church that he leads, the Catholic Church. Those Protestants who are justified before God, those Muslims who have found favor with God have only reached a state of grace through Jesus Christ the Head and, consequently, through His Body, the Catholic Church. Any grace that is received by men flows from the capital grace of Jesus Christ that nourishes the rest of the Body. All men must seek full union with the Successor of Peter lest they risk eternal damnation. If our rhetoric and dispositions contradict this ancient teaching we will continue to witness the negative results of the past fifty years, for this teaching affects our understanding of the whole Deposit of Faith. If we capitulate on this teaching, we will surrender the essential meaning of Christianity.
Ceasing to proclaim the Church’s uniqueness, the faithful will continue to subjugate the dogmas of Tradition to their own spiritual experiences and sentiments, interpreting them more and more through the lens of our sentimental age. This subjugation skews the very meaning of the words we use to communicate the Faith. Catholic dogma is interwoven with the unique mediation of the Church, for not only through Her are they properly defined, but also their concrete meaning is preserved in relation to Her own uniqueness. There is a direct relation: the further Catholics move from the necessity of the Church, the more nebulous and vague will Her Teachings be understood.
Traditional words and phrases are beginning to lose their punch and clarity. Just as moral words have lost their power in the West, so too will many dogmatic words and propositions in the Church. For example, take the word “faith.” Without acknowledging the Church’s uniqueness, this word is losing its intrinsic connection to the Church which makes faith possible so that we might embrace all that God has revealed through Her. Instead, many Catholic communities use the word to express an emotive response that has no explicit relation to Revelation or to the Church.
Ask your average Catholic what “hope” means. Ask him to define “worship” or “prudence” or “Church.” I have found that most of the time these words are no longer used for the transmission of Tradition but, rather, are used to express an emotive response whose meanings have long been forgotten.
Even many truths still retained have become accidental to the spiritual experiences that are sought. Western emotivism is becoming the real motivation for spirituality, cutting the individual off from the transformative power of the objective truths of Tradition handed down and preserved by the Catholic Church. Lewis’s Uncle Screwtape could not have devised a better plan for destroying the faith of so many men.
And, of course, from this proceeds a host of other errors that the faithful have been resisting the past fifty years. If the Church is not necessary, we have no real need to evangelize. Instead, let us join hands with those who love God proclaiming the victory of the Gospel that transcends all churches, including the Catholic Church. The unity of Christians, it is assumed, can be found outside that hierarchical institution. We must be on our guard against such reasoning. Even the “new evangelization” has become a catchphrase, a euphemism for the melting pot of the different Christian sects. There is no surer way to destroy the Great Commission than to accept this relativism of denominationalism.
But what is most dangerous for you and me is the grave sin of presumption that is lurking at the door. Providence has willed to bring men into Divine Life through the Church. To applaud non-Catholics for their love of God (a very laudable quality indeed!) without insisting on the indispensable mediation of the Church welcomes a false understanding of the depravity of man and the holiness of God. We would dare have God on our own terms, insisting that his mercy is owed us. Surely our hearts are not so dark and deceptive that God’s mercy will not reach us. Surely, we can have the Groom without His Bride. God is good, and our sins are not so grave.
This kind of presumption blinds us to our own wickedness, our own deceit and self-love. Deceit and self-love--the two great vices guarding the hearts of men from the loving gaze of the Holy Trinity. These cancers of the soul are not easily killed; they lie hidden, ever waiting to reassert themselves. Without the Church, without Her means of grace, we are damned to love ourselves over God and neighbor forever.
May we draw close to our Mother, the Church, for we are only fed through Her. We are only in Jesus Christ in so far as we draw near to Her. We evangelize our neighbors to the degree that we draw them into the Catholic Church.
Written by Nick Trosclair, Co-founder & Tutor of Saint John of the Cross Academy.
2. De ecclesiae catholicae unitate; Jurgens: volume one of his The Faith of the Early Fathers, 221. “Habere non potest Deum patrem qui Ecclesiam non habet matrem.
3. Adista, February 26, 2001; Ferrara/Woods, The Great Facade, 195)
4. Ferrara/Woods, The Great Facade, 204.
5. Matthew 18:6
6. Hardon, John, The Catholic Catechism, 234-236; also see Fr. Hardon’s excellent essay online: http://www.therealpresence.org/archives/Church_Dogma/Church_Dogma_032.htm
7. Writing in the 6th century, St. Fulgence of Ruspe writes in his The Forgiveness of Sins: “Anyone who is outside this Church, which received the keys of the kingdom of heaven, is walking a path not to heaven but to hell.” Jurgens: Volume. 3, FCF p. 292.
8. Augustine writes in his Discourse to the People of the Church at Caesarea: “A man cannot have salvation, except in the Catholic Church. Outside the Catholic Church he can have everything except salvation. He can have honor, he can have sacraments, he can sing alleluia, he can answer amen, he can possess the gospel, he can have and preach faith in the name of the Father and of the Son and of the Holy Spirit; but never except in the Catholic Church will he be able to find salvation.” Jurgens: Vol. 3, FCF, 130.
9. St. Ignatius writes to the Philadelphians: “Those indeed, who belong to God and to Jesus Christ--they are with the bishop. And those who repent and come to the unity of the Church--they too shall be of God, and will be living according to Jesus Christ. Do not err, my brethren: if any follow a schismatic, he will not inherit the Kingdom of God.” Jurgens, FEF, Volume 1, 22.
10. St. Irenaeus writes in his Adversus Haereses: “For she (the Church) is the entrance to life, while all the rest are thieves and robbers. That is why it is surely necessary to avoid them, while cherishing with the utmost diligence the things pertaining to the Church, and to lay hold of the Tradition of truth.” Jurgens, FEF, Volume 1, 91.
11. St. Cyril of Jerusalem writes in his Catechetical instructions: “And if ever you are visiting in cities, do not inquire simply where the House of the lord is,--for the others, sects of the impious, attempt to call their dens the Houses of the Lord,--nor ask merely where the Church is, but where is the Catholic Church. For this is the name peculiar to this holy Church, the Mother of us all, which is the Spouse of our Lord Jesus Christ, the only begotten Son of God.” Jurgens, FEF, Volume 1, 347)
12. St. Jerome writes in his Letter to Pope Damasus: “I follow no leader but Christ and join in communion with none but Your Blessedness, that is, with the chair of Peter. I know that this is the rock on which the Church has been built. Whoever eats the Lamb outside this house is profane. Anyone who is not in the ark of Noah will perish when the flood prevails.” Jurgens, FEF, Volume 2, 183-184.
13. Lumen Gentium II, 14: “[The Council] relies on sacred Scripture and Tradition in teaching that this pilgrim Church is necessary for salvation. Christ alone is the mediator of salvation. He presents himself to us in His Body, which is the Church.”
14. Ludwig Ott writes: “The Fourth Lateran Council (1215) declared: ‘The universal Church of the faithful is one outside of which none is saved.’ This was the teaching also of the Union Council of Florence, and of Pope Innocent III and Boniface VIII in the Bull ‘Unam Sanctam,’ Clement VI, Pius XII in the Encyclical ‘Mystici Corporis.’ As against modern religious indifferentism, Pius IX declared: ‘By Faith it is to be firmly held that outside the ApostolicRoman Church non can achieve salvation. This is the only ark of salvation. He who does not enter into it, will perish in the flood. Nevertheless equally certainly it is to be held that those who suffer from invincible ignorance of the true religion, are not for this reason guilty in the eyes of the Lord.’(Fundamentals of Catholic Dogma 312)
15. see Catholic philosopher Alasdair MacIntyre’s After Virtue for a thorough demonstration of this claim.
16. Dietrich Von Hildebrand noted the same thing about the liturgy: “"Truly, if one of the devils in C.S. Lewis' The Screwtape Letters had been entrusted with the ruin of the liturgy he could not have done it better."