On "The O'Reilly Factor" tonight, Dr. Ben Carson refused to engage in a war of words with fellow GOP candidate Donald Trump, after saying on Wednesday that the depth of the two contenders' faith was "probably the biggest" difference between them.

Trump called in to CNN's "New Day" on Thursday to react to Carson's comments, dubbing him just an "OK doctor. Trump also said, "You look at his faith and I think you're not going to find so much."

"If you look at his past, which I've done, he wasn't a big man of faith. All of a sudden he's becoming this man of faith. And he was heavy into the world of abortion," Trump said.

Carson told Bill O'Reilly tonight that it wasn't his intention to impugn Trump's religious beliefs.

"I really don't want to get into the mud pit. That's not in my nature," Carson said. "I know that the media frequently likes to stoke up these things, and they goad people into silliness."

Carson said that he's going to differentiate himself from the other candidates not by putting them down, but by focusing on what he believes and what he stands for.

Watch the "O'Reilly Factor" interview above.