10/30/2009 AT 07:00 AM EDT
Sure, he's got Demi Moore
. But Ashton Kutcher
's wife isn't the only No. 1 in his life.
"My best friend? Yehuda Berg," Kutcher, 31, announced Wednesday night at GQ
magazine's The Gentleman's Ball in New York City, where he presented the Kabbalist with an award for being an agent of change. "To me, he's not a rabbi. He's my friend."
Kutcher went on to explain, "If you truly want to change the world, you have to start by changing yourself. [Berg] taught me that and it's been the most important lesson of my life."
Though the star wouldn't specify how he's changed himself, the rabbi provided further explanation.
"We used to think, 'Change the world, and eventually, my life will be better,' " Berg said. "The truth is, if we change ourselves, the world will be better."
As for an A-list relationship like Kutcher and Moore's, what does the rabbi believe to be the key to their success?
"There has to be an understanding of each other," says Berg, who also counts Madonna
and Gwyneth Paltrow
among his followers. "And an understanding that we can be different, but we don't have to be apart."
And now that the world knows how Kutcher feels about Berg, how would the rabbi describe the star and his wife? "They're very special people," Berg says. "And she's a great mom. An amazing, amazing mom."