Rupert Murdoch, News Corp. chief executive and outspoken octogenarian media mogul, took to Twitter on Sunday to weigh in on the breakup of Tom Cruise and Katie Holmes. And Murdoch's tweets about Scientology sparked a big backlash.

[Slideshow: The end of 'TomKat']

"Scientology back in news," Murdoch tweeted. "Very weird cult, but big, big money involved with Tom Cruise either number two or three in [hierarchy]."

The owner of Fox News, Wall Street Journal and New York Post followed the "cult" comment with another tweet.

"Watch Katie Holmes and Scientology story develop," Murdoch wrote. "Something creepy, maybe even evil, about these people."

While Cruise is often associated with Viacom's Paramount Pictures, the Los Angeles Times noted, he has also starred in films for 20th Century Fox--the studio owned by News Corporation--and is "known for being prickly about being challenged about his involvement with Scientology."

[Related: Custody, images at stake in Cruise-Holmes divorce]

Murdoch, though, is standing by his comments.

"Since Scientology tweet hundreds of attacks," he wrote later. "Expect they will increase and get worse and maybe threatening. Still stick to my story."

After a user asked Murdoch for his thoughts on Mormonism, he responded: "Mormonism a mystery to me, but Mormons certainly not evil."

Earlier Sunday, Murdoch used Twitter to criticize Mitt Romney's campaign.

"Met Romney last week," Murdoch wrote. President Barack Obama's re-election campaign--comprised of "tough" Chicago political veterans--will be tough to beat, Murdoch added, unless Romney "drops old friends from team and hires some real pros. Doubtful."

It's not the first time the 81-year-old has expressed his doubts about Romney's electability. Last week, Murdoch tweeted: "When is Romney going to look like a challenger? Seems to play everything safe, make no news except burn off Hispanics."