John Roberts is a Catholic.
From: Jerry Filteau, "Alito would be fifth Catholic on Supreme Court", posted on Catholic News Service website, 31 October 2005 (http://www.catholicnews.com/data/stories/cns/0506179.htm; viewed 31 October 2005):
Other Catholics currently on the nation's highest bench are recently appointed Chief Justice John Roberts and Justices Antonin Scalia, Anthony Kennedy and Clarence Thomas.From: Rachel Zoll (Associated Press), "Alito would tip court to Catholics: If nominee's confirmed, members would hold majority for 1st time", published in The Indiana Star, 2 November 2005 (http://www.indystar.com/apps/pbcs.dll/article?AID=/20051102/NEWS06/511020482/1012; viewed 2 November 2005):
Newly installed Chief Justice John Roberts, the fourth Catholic [currently on the U.S. Supreme Court], is solidly conservative, and his wife, Jane, volunteers for Feminists for Life. But it is unclear how he will vote on abortion cases.