This episode's headline: Catholicism in America; Political Wrap; The Candidates. In New York: ROBERT MAC NEIL; In Washington: JAMES LEHRER; GUESTS: REV. ANDREW GREELEY Author, Sociologist; LINDA CHAVEZ, Center for Equal Opportunity;SISTER MAUREEN FIEDLER, Catholics Speak Out; RICHARD RODRIGUEZ, Pacific News Service; GEORGE WEIGEL, Ethics in Public Policy Center; MARK SHIELDS, Syndicated Columnist; PAUL GIGOT, Wall Street Journal; ARTHUR FLETCHER, Republican Presidential Candidate; CORRESPONDENTS: RICHARD OSTLING; ELIZABETH FARNSWORTH