What Is Meant By A Catholic?

In you question you have given the title of a book that has been written by Richard Rohr in association with Joseph Martos. True to its title, the book is raising and also answering the question about why a person should have his faith in Catholicism and should follow its rituals.
      
We can also view the situation in accordance with our own view and if you view the people of the catholic faith a few years back, they just accept the faith if they are born in the catholic family. But the younger generation is not following that path, they are questioning that why this very faith and why there be any faith at all. Why is a faith necessary?
     
If we view theses questions, the book is certainly a good one as younger generation will learn a few things from it that can help them in the future.