Actually the use of the term “Catholic Church” was already in existence from 88 and back-not later or in the 4th Century as Protestants would want us to believe.
Here is the proof from an early Christian;
St. Clement I, A.D 88-97: “Heretical teachers pervert Scripture and try to get into Heaven with a false key, for they have formed their human assemblies later than the Catholic Church. From this previously-existing and most true Church, it is very clear that these later heresies, and others which have come into being since then, are counterfeit and novel inventions.” (Epistle to the Corinthians)
Later, St. Athanasius(the one who assembled the Scriptures we use today) said;
“How then can they be Christians, who for Christians are Ario-maniacs ? Or how are they of the Catholic Church, who have shaken off the Apostolical faith, and become authors of fresh evils?” (Discourses against the Arians 400 AD)
Notice that Ignatius would fall in between Clement and Athanasius yet he was a student of John the beloved disciple of Jesus.
Bottom line: There were no Protestant churches until Luther. Thus Protestantism is a false copy of the true church. A counterfeit and novel invention. The Early Church Fathers were clearly Catholic, some of them even knew the apostles first hand! While some Protestants try to claim that the “real church” was underground or silent, there is no evidence for this. We already know that the early Catholic church did go underground (literally, i.e. the catacombes) due to persecution from Emperors and pagans.
The truth is all around you but you chose to cling to what your pastors tell you other than the Church-which is the pillar and ground of truth(1 Timothy 3:15).