What does it mean to identify oneself as "Catholic"?

I asked that question earlier today.  A reader responds with a quote from Walker Percy:

"What distinguishes Judeo-Christianity in general from other world religions is its emphasis on the value of the individual person, its view of man as a creature in trouble, seeking to get out of it, and accordingly on the move. Add to this anthropology the special marks of the Catholic Church: the sacraments, especially the Eucharist, which, whatever they do, confer the highest significance upon the ordinary things of this world, bread, wine, water, touch, breath, words, talking, listening––and what do you have? You have a man in a predicament and on the move in a real world of real things, a world which is a sacrament and a mystery; a pilgrim whose life is a searching and a finding."-- Walker Percy, "The Holiness of the Ordinary" (from Signposts in a Strange Land)