Kelsey Grammer sat down with Bill O'Reilly Monday night to reflect on his role in "Killing Jesus," the movie based on O'Reilly and Martin Dugard's best-selling book.

O'Reilly noted that the audience will be surprised to see the former "Cheers" and "Frasier" star playing the very evil role of King Herod the Great.

"It's fine. I'm an actor. You lend yourself to the role. It doesn't necessarily reflect on you," Grammer said, when asked about playing the role of a bad guy.

Grammer said in researching the role, he learned that King Herod had killed half of his 30-40 children and was probably very paranoid about being assassinated. 

The role of Jesus was played by young actor Haaz Sleiman. O'Reilly asked Grammer whether he had any advice for Sleiman on the daunting challenge. 

"I don't really do that. I just tell guys to just go for it. You know in your heart - because I think we're all connected - everything you need to know to play anything you're told to play. And it will come," he said. 

Watch the "Killing Jesus" trailer below and tune in to "The O'Reilly Factor" on Wednesday at 8p ET to hear from Sleiman

Catch the premiere of "Killing Jesus" on the National Geographic Channel, Sunday at 8/11p ET.