Now, I don't think you should change your views because of what these celebrities think, but I did think it was interesting to see who were self proclaimed athiests and agnostics. I've posted just some of the ones I came across. Some won't be a surprise, but others might be.
You can find a more extensive list here:
http://www.celebatheists.com/wiki/index.php?title=Main_Page
Athiests: Lance Armstrong, Lewis Black, Marlon Brando, Warren Buffett, Bill Bryson, Noam Chomsky, Chumbawamba, Roger Ebert, Albert Einstein, Jodie Foster, Bill Gates, Ricky Gervais, Seth Green, Katharine Hepburn, Billy Joel, Angelina Jolie, Diane Keaton, John Malkovich, Barry Manilow, Sir Ian McKellen, Jack Nicholson, Ron Regan Jr., Keanu Reeves, Steven Soderbergh
Agnostics: Piers Anthony, Charles Darwin, Richard Dreyfuss, Matt Groening, Larry King, Dave Matthews, Sean Penn, James Taylor, Uma Thurman, Ted Turner
Ambiguous: David Bowie, George Clooney, David Duchovny, Dave Grohl, Stephen Hawking, Sir Edmund Hillary, Stan Lee, Monica Lewinsky, G. Gordon Liddy, Bill Mahr, Marilyn Manson, Sarah McLachlan, Natalie Portman, Christopher Reeve, Andy Richter, William Shatner, Tool, Mark Twain, Gene Wilder, Bruce Willis