Holmes' apparent conversion plans were the latest in the very public romance between the 42-year-old Cruise and 26-year-old Holmes, who said she grew up dreaming that she would marry Cruise one day.
Cruise told Entertainment Weekly he is confident he will marry the actress.
"It's gonna happen, man. It'll happen," said Cruise, who also said Holmes "digs" his religion.
Holmes, who was raised Roman Catholic, told Access Hollywood she is a big fan of the church founded by L. Ron Hubbard.
"I have looked into it myself, and I really like it, and I think it's really wonderful," Holmes said.