Rev José Mario O Mandía
The term “Catholic” comes from the Greek adjective καθολικός (katholikos), meaning “universal,” all-encompassing. The term was first used back around the year 107 AD by one of the Church Fathers, Saint Ignatius of Antioch, in his Letter to the Smyrnaeans. He is quoted by the CCCC (no 166): “The Church is catholic, that is universal, insofar as Christ is present in her: ‘Where there is Christ Jesus, there is the Catholic Church’ (Saint Ignatius of Antioch).”
The same point of the CCCC enumerates three reasons why the Church is called catholic or universal. “ The Church proclaims the fullness and the totality of the faith;  she bears and administers the fullness of the means of salvation;  she is sent out by Christ on a mission to the whole of the human race.”
 Regarding the first, the Church teaches everything that the Lord Jesus Christ has taught about God, about ourselves and the world, about how we can be saved and be holy. She can do this because she possesses the wealth of Apostolic Tradition directly received from Jesus Christ. This Apostolic Tradition is found in the Sacred Scriptures and Sacred Tradition (see Bite-Size Theology nos 17 and 23) and is entrusted to the teaching office (Magisterium) of the Church (see BST 24).
 As for the second, Jesus Christ has instituted the sacraments for our sanctification and entrusted these to the Church. He has particularly entrusted to the Church a most precious gift: that of His Most Body and Blood. This gift comes to us in the only sacrifice that redeems us and which is made present once more in each Mass. All the graces we need to get to heaven can be obtained in the Catholic Church. Because the Church teaches everything that we need to know (first reason), and possesses all the sources of grace and strength (second reason), she is like a “one-stop shop.” There is no good and holy thing in any other religion which one will not find in the Catholic Church.
The Catholic Church has got it all!
 Regarding the third point, the “target market” of the Church is everyone, with no exception. The CCCC (172) explains the reason for this: “The Church must do so because Christ has given the command: ‘Go therefore and make disciples of all nations, baptizing them in the name of the Father and of the Son and of the Holy Spirit” (Matthew 28:19). This missionary mandate of the Lord has its origin in the eternal love of God who has sent his Son and the Holy Spirit because ‘he desires all men to be saved and to come to the knowledge of the truth’ (1 Timothy 2:4).”
However, this third explanation of the Church’s catholic nature also means that every single member of the Church, whether he be Pope, bishop, priest, religious or lay person, healthy or sick, young or old, rich or poor, has a mission. The mission is also “catholic” in that sense. This is why the CCCC (173) teaches: “The Church, guided by the Holy Spirit, continues the mission of Christ himself in the course of history. Christians must, therefore, proclaim to everyone the Good News borne by Christ; and, following his path, they must be ready for self-sacrifice, even unto martyrdom.”