Protestant propaganda has somehow affected the mentality of some Catholics, they no longer believe that the Church is necessary for salvation. What they thought is that having faith in God and doing good works are enough to attain salvation. If confronted with the truth that the Church is necessary for salvation they are quick to dismiss this fact by saying that the Church is silent about such a teaching. But the reality is the Catholic Church is not silent about it, here are some of the teachings of the Church regarding the necessity of the Church for salvation. Every Catholic must know the official teachings of that Church so that they will not be influenced by heretical teachings of the Protestants.
This Church was founded not by man, but by the immortal God Himself, who built her upon a most solid rock. The Highest himself, says the Prophet, hath founded her. Hence, she is called the inheritance of God, the people of God. The power which she possesses is not from man but from God. . .We are, therefore, bound to believe that there is one Holy Catholic Church. With regard to the Three Persons of the Holy Trinity, the Father, the Son, and the Holy Ghost, we not only believe in them but also believe in them. [The Catechism of Trent, Article IX]
For although it is evident from the word of the Lord Himself in the Sacred Gospel [Cf. Matt. 16:18] where the Church is established, let us hear nevertheless what the blessed Augustine, mindful of the opinion of the same Lord, has explained. For he says that he Church of God is established among those who are known to preside over the apostolic sees, through the succession of those in charge, and whoever separates himself from the communion or authority of these sees, is shown to be in schism. And following additional remarks, he says: “If you are put outside, for the name of Christ you will also die, Suffer for Christ among the members of Christ, clinging to the body, fight for the head”. [Dilectionis vestrae to the schismatic bishops of Istria, 585]
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 form Catholic unity, can attain eternal life. Indeed this is certainly quite contrary to Catholic teaching. . .The Catholic dogma that no one can be saved outside the Catholic Church is well-known: and also those who are 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.” cannot obtain eternal salvation. [Pius IX, Quanto Conficiamur Moerore, to the bishops of Italy]
This Holy Council first of all turns its attention to the Catholic faithful. Basing itself on Sacred Scripture and Tradition, it teaches that the Church, a pilgrim now on earth, is necessary for salvation: the one Christ is mediator and the way of salvation; he is present to us in his body which is the Church. He himself explicitly asserted the necessity of faith and baptism, and thereby affirmed at the same time the necessity of the Church which men enter through baptism as through a door. [Second Vatican Council, Lumen Gentium No.14]
For it is through Christ’s Catholic Church alone, which is the universal help towards salvation, that the fullness of the means of salvation can be obtained. [Second Vatican Council, Decree on Ecumenism No3]
These are few quotations from Magisterial teachings that proves the the belief that the Church is necessary for salvation is an official teaching of the Catholic Church. The Church gives three reasons why the Church is necessary for salvation.
1. The Catholic Church was founded by Jesus Christ. Henceforth, his followers should be in this Church (Acts 2:47, Eph. 5:23)
2. The origin of the authority of the Catholic Church is not human but divine (Mt. 16:17-19)
3. It is only through the Church where sanctifying grace is being dispense through the Sacraments.
The belief that the Church is necessary for salvation was not invented by the Fathers of the Church but in fact it is based on Sacred Scripture and Tradition.