The Church is called Catholic or universal because it has spread throughout the entire world, from one end of the earth to the other. Again, it is called Catholic because it teaches fully and unfailingly all the doctrines which ought to be brought to men’s knowledge, whether concerned with visible or invisible things, with the realities of heaven or the things of earth. Another reason for the name Catholic is that the Church brings under religious obedience all classes of men, rulers and subjects, learned and unlettered. Finally, it deserves the title Catholic because it heals and cures unrestrictedly every type of sin that can be committed in soul or in body, and because it possesses within itself every kind of virtue that can be named, whether exercised in actions or in words or in some kind of spiritual charism.
-Saint Cyril of Jerusalem
From the Liturgy of the Hours, Office of Readings, Second Reading, Wednesday in the 17th Week of Ordinary Time