The Holy Roman Catholic and Apostolic Church used to publicly teach this truth but it no longer does, probably owing to Ecumenism - The Universal Solvent of Tradition.
However, the truth remains even if it is not publicly taught. Roman Catholic Traditonalists know they have enemies and they know who they are - the same enemies of God and His Holy Roman Catholic and Apostolic Church, outside of which there is neither Salvation or Sanctification
Here is an excerpt from The Roman Catechism, the one Catechism Raider Fan prefers over all others.
The true Church is also to be recognised from her origin, which can be traced back under the law of grace to the Apostles; for her doctrine is the truth not recently given, nor now first heard of, but delivered of old by the Apostles, and disseminated throughout the entire world. Hence no one can doubt that the impious opinions which heresy invents, opposed as they are to the doctrines taught by the Church from the days of the Apostles to the present time, are very different from the faith of the true Church.
That all, therefore, might know which was the Catholic Church, the Fathers, guided by the Spirit of God, added to the Creed the word Apostolic. For the Holy Ghost, who presides over the Church, governs her by no other ministers than those of Apostolic succession. This Spirit, first imparted to the Apostles, has by the infinite goodness of God always continued in the Church.
And just as this one Church cannot err in faith or morals, since it is guided by the Holy Ghost; so, on the contrary, all other societies arrogating to themselves the name of church, must necessarily, because guided by the spirit of the devil, be sunk in the most pernicious errors, both doctrinal and moral.
And just as this one Church cannot err in faith or morals, since it is guided by the Holy Ghost; so, on the contrary, all other societies arrogating to themselves the name of church, must necessarily, because guided by the spirit of the devil, be sunk in the most pernicious errors, both doctrinal and moral.