Nicole Kidman is a Catholic, although the extent of her activity within that denomination is not entirely clear.
Nicole Kidman was married for many years to acting superstar Tom Cruise, who is perhaps the world's most famous devout Scientologist. It has widely been reported that Nicole Kidman was also a Scientologist, but there are conflicting reports about this. Whether or not Nicole Kidman was officially a member of the Church of Scientology, she was clearly heavily involved with the denomination through her marriage. Since the breakup of her marriage to Cruise she has stated that she is not a Scientologist.
From: Tilman Hausherr, scientology celebrities FAQ" of alt.religion.scientology, last updated 1 July 2005 (http://home.snafu.de/tilman/faq-you/celeb.txt; viewed 11 November 2005):
Name: Nicole "nic" Kidman
Status [in Scientology]: probably not a scientologist
Achievement: wife of Tom Cruise, Far and Away, Batman forever, Golden Globe for To Die For
Sources [confirming that she was in Scientology]:
She is frequenly mentioned as a scientologist, but in The Sydney Morning Herald's Good Weekend (a Saturday supplement magazine) Sat 1/2/97 she says she is not a Scientologist.
In LA Magazine 10/93 Tom Cruise suggests she is one.
The East Grinstead Observer of 30.8.2000 mentions that Tom Cruise and Nicole Kidman are sending their children to... Scientology "Greenfields School". But the New York Post 7.2.2001 said that they are going to school in Sydney.
From: "Religious Affiliations of Celebrities" page in "Celebrity Religion" section of "Religion Facts" website (http://www.religionfacts.com/celebrities/religions_of_celebrities.htm; viewed 27 April 2007):
Below is an index of the religious affiliations or belief systems of celebrities (both living and dead; in film, television, music, literature, academics and politics), listed in alphabetical order by last name...
Celebrity: Nicole Kidman
Quotes, More Information, Sources:
The award-winning actress was raised Catholic and has increasingly returned to her religious roots since divorcing Scientologist Tom Cruise. "Catholicism guides me. I certainly have a strong belief. I try to go to church regularly, and I try to go to confession." - Catholic.org [link to: http://www.catholic.org/hf/marriage/story.php?id=20148]