First off, don't cry for me, Argentina. I knew what I was getting into when I went on the Letterman program last week. The man doesn't like me, even though by his own admission, he has no idea what I do here on "The Factor." He doesn't watch it, nor has he read any of my books.

Hostility and a lack of information is never a good combination, but a billoreilly.com poll indicated you wanted me to chat again with Dave. And my book "Culture Warrior" is, of course, in play. So I ventured into Dave's world in a program taped last Monday, a week ago, and found the comedian to be tense.

Almost instantly, I had to make a decision. Should I let him have it? Or should I let him wander down the boorish highway alone? Incredibly, I chose the latter. I restrained myself for once. Believing Letterman wanted to goad me into an insult session. Why should I accommodate him?

So I left his studio believing the folks could make up their own minds about Letterman and O'Reilly. But then, three days later, when I could not reply to him, Letterman promo'd my Friday appearance on his Thursday night program. And I sat there in disbelief as he said this:

(BEGIN VIDEO CLIP)

DAVID LETTERMAN, HOST OF "LATE SHOW WITH DAVID LETTERMAN": Bill O'Reilly will be on the show.

Now Bill O'Reilly was on the show. He's been on many, many times. And the last time he was on the show, I caught him lying.

And I said to myself, well, you better do something. You can't sit here and let this guy lie.

(END VIDEO CLIP)

Letterman caught me lying? What lie was that? There's no lie apparent in my appearance with him last January. Check the transcript. And we called his office to find out what he referring to. His staff couldn't find define a lie either.

So my following words are directed personally to David Letterman this evening: There was no lie, sir. Your statement was false and cheap. You owe your audience and me an apology. I hope you're man enough to give it.

Now the big picture: What's behind Letterman's demeanor? There's no question he lives in the left-wing precincts. He's entitled to do that. He's good friends with Al Franken — aka Stuart Smalley — the king of personal attacks, and with some other far-left type of partisans.

Like many true believers, Mr. Letterman's not all that interested in hearing opposing points of view. If he was, he'd tune into "The Factor" once in a while, so he and I could at least have an intelligent conversation. But Letterman isn't after information. He's in the choir and wants to sing, no matter how shrill the note.

Unfortunately, millions of Americans on both sides of the ideological spectrum drink the same kind of Kool-Aid Letterman does. They simply want to demean people with whom they disagree.

Letterman-O'Reilly debates are a signature moment in the culture war. So I'm glad I went behind enemy lines again. Dave is a cultural icon whose attitude reaches millions of people every day. And now everybody knows what he's all about, which is a very good thing.

And that's the Memo.

Most Ridiculous Item of the Day

At 9:15 Eastern Time — just a few minutes from now — we'll have our first-ever press conference on BillOReilly.com, without the press. Just for you. You can e-mail me questions. See me answer them on your P.C.

Conference will be repeated on BillOReilly.com throughout the week, so you'll have plenty of chances to see it. But it all unfolds live in about 18 minutes from now.

Ridiculous? We'll see.

—You can catch Bill O'Reilly's "Talking Points Memo" and "Most Ridiculous Item" weeknights at 8 and 11 p.m. ET on the FOX News Channel and any time on foxnews.com/oreilly. Send your comments to: oreilly@foxnews.com