During her appearance on SiriusXM's The Jess Cagle Show this week, O'Donnell, 59, spoke about why she'll "always love" the Mission: Impossible actor, 58, even if she does not "understand" his Scientology beliefs.
"He is the only person who never misses my birthday. In knowing him for 25 years now, he has never missed my birthday or an event in my life," said O'Donnell. "Now, I don't know him enough to go, 'Hey, Tommy, it's Ro, the Scientology thing -- can we chat?' Like, that's not my relationship with Tom Cruise. I don't have his home phone number."
"I know people think in Hollywood and celebrity [that] everybody knows each other, but I know him in the way that I did in that time 25 years ago," she added. "But every year, I think what a classy guy he is that he never has forgotten my birthday."
Continuing, she said, "A lot of people say to me it's just his secretary, but I don't believe that. I think he knows in early March, 'Oh, it's Rosie's birthday coming up,' and he sends me something. Every single year for 25 years."
Bruce Glikas/WireImage; Ethan Miller/Getty
Want to get the biggest stories from PEOPLE every weekday? Subscribe to our new podcast, PEOPLE Every Day, to get the essential celebrity, entertainment and human interest news stories Monday through Friday.
"I love Tom Cruise and I will always love Tom Cruise. I do not understand, you know, the Scientology religion," O'Donnell added during the interview, also calling the controversial church "scary." She went on to praise former Scientology member Leah Remini, who is now one of its most vocal critics.
Jeff Kravitz/FilmMagic Tom Cruise and Rosie O'Donnell in 2001
RELATED GALLERY: Celebs You Didn't Know Were Friends
In December, O'Donnell shared a photo on Instagram of a Christmas gift she received from Cruise. The gold-decorated gift had a message that read, "To: Rosie O'Donnell. Warmest wishes to you this Holiday Season --Tom Cruise." She captioned the photo, "Christmas is here when tommy's gift shows up #holidayseason."
Cruise previously appeared as a guest on The Rosie O'Donnell Show, which ended in 2002, bringing her a bouquet of flowers and hugging the talk show host when he was promoting his movie Vanilla Sky back in 2001. She told him in that TV interview, "I enjoy you a lot. I know you know it."