Glenn Beck apologized for making a comparison between Reform Judaism rabbis and "radicalized Islam," saying it was "one of the worst analogies of all time."

"Somebody has called me ignorant for what I said on Tuesday and I think that's a pretty good description of my -- what I said," Beck said on his radio show Thursday. He added, "I made one of the worst analogies of all time and I knew it when I said and I just kept going... It was a nightmare and I knew it."

On his radio show Tuesday, Beck started out by saying Reform rabbis are "generally political in nature."

"It's almost like Islam, radicalized Islam in a way, to where it is just -- radicalized Islam is less about religion than it is about politics. When you look at the Reform Judaism, it is more about politics. I'm not saying that they're the same," he said. "It's not about terror or anything else, it's about politics, and so it becomes more about politics than it does about faith. Orthodox rabbis -- that is about faith."

Jewish groups responded quickly. Rabbi David Saperstein, Director of the Religious Action Center of Reform Judaism told Haaretz [5] that Beck's comments were “deeply offensive, completely absurd.”

In his broadcast Thursday, Beck, who often implores his audience to do their homework on issues of the day, explained that his analogy sprung from something he had heard Monday night from a friend and failed to check.

"I was having a conversation with a few friends the night before, one of whom I trust on things like this, and I'm not even sure if I misunderstood him or misheard him or what but I certainly had not done enough homework to go on the air and haphazardly make a comment like I did," he said.

Watch Beck's apology: