"I'm not a racist."

Why is it that, in the interests of authenticity, transparency—and to salvage a career—a person will confess to all manner of sins, from porn addiction, drug abuse and infidelity to violent crime and even child abuse. But they won't admit to being a racist.

In defending his vitriolic, n-word-filled attack on a black heckler at a 2006 comedy show, Seinfeld's Michael Richards contended, "I'm not a racist."

In a recent recorded phone conversation, Dog the Bounty Hunter's Duane Chapman repeatedly used a racial slur to describe his son's girlfriend. He assures us it was taken out of context.

Whether following a police beat-down or a road-rage incident, the commonly-uttered defense "I'm not a racist" is usually thrown out to protect one from accusations of what has now become the unforgivable sin.

It's become perfectly fashionable for a community leader to admit to all manner of indiscretions with reassurances such as "Nobody's perfect," "I made a mistake" and "I'm working through my issues with a counselor."

But I'm guessing it's going to be a while before you hear someone say something like this: "I've been dealing with ethnic prejudice for years. Bottom line is, I'm a racist, and I need help. I've been hiding this dark side of myself very well, but in a time of stress, my true colors were revealed."

In an age when public confession has become a mark of authenticity, one is more likely to hear a straightforward admission of criminal offense such as drug possession, prostitution or tax fraud than a perfectly legal social offense like racism, sexism or homophobia.

It's clear that some sins are still taboo ... and not the ones we would expect.