Richard Cohen’s column is mainly about Barack Obama, but it is also about how all of the candidates have fibbed.

John Edwards lied about the cost of his haircuts. Fred Thompson lied about lobbying for a pro-choice outfit. John McCain insists that the United States was founded as a “Christian nation.” Mitt Romney concocted the story about how his father marched with Martin Luther King Jr. And Rudy Giuliani is a one-man fib machine — everything from why he had to provide police protection for his then-mistress to the survivability rates for prostate cancer in Britain.

Now a lot of this is overdone. I think Giuliani is using misleading statistics about cancer in Britain, but I have no reason to think that he himself believes they’re misleading. But it’s the bit about McCain that’s most irritating, since McCain has backed down from that assertion. Instead of “insists that” Cohen should have written “once said that.” But here’s Cohen again, at the end of his column: “When John McCain sticks to his insistence that the Constitution established the United States as a ‘Christian nation,’ I don’t like it, but I know McCain and I know his character. . .”