It is one of life’s great mysteries that so many liberal people are so callous when it comes to aborting fetuses. I mean, the Democratic convention last summer was almost a pro-abortion pep rally, as a variety of pro-choice speakers, including Caroline Kennedy, knelt at the altar of “reproductive rights.”

Recently, another woman who calls herself a Catholic, Mary Elizabeth Williams, wrote a shocking article for Salon. Entitled “So What if Abortion Ends Life?” Williams starkly states: “I believe that life starts at conception. And it’s never stopped me from being pro-choice.”

Williams says this about her own pregnancies: “I never wavered for a moment in the belief that I was carrying a human life inside of me.”

.And she continues, “Here’s the complicated reality in which we live: All life is not equal. That’s a difficult thing for liberals like me to talk about... (A) fetus can be a human life without having the same rights as the woman in whose body it resides. She’s the boss. Her life and what is right for her circumstances and her health should automatically trump the rights of the non-autonomous entity inside of her. Always.”

So now a developing fetus or viable baby ingesting in the womb is a “non-autonomous entity.” Good grief!

The measure of a decent human being is how he or she treats the defenseless. The philosophy of Williams echoes past tyranny: Might makes right! What gives Williams the right to determine that her life is better than the baby she carries? Who appointed Williams the arbiter of who lives and who dies? Always, Williams? Abortion is acceptable always?

You may remember the late-term abortion doctor George Tiller. Tiller had an assistant in his Kansas clinic, Dr. Ann Kristin Neuhaus, whose assignment was to put on paper a reason for the late termination. Pretty much any reason would do, including “anxiety.”

On May 31, 2009, Tiller was shot through the eye while attending a church service. His killer, Scott Roeder, is serving life in prison. The murder made national headlines, and in many press dispatches, Tiller was portrayed as a martyr. People like me who had criticized Tiller before the vicious crime were accused by far-left loons of encouraging the assassination.

On June 22, 2012, Neuhaus was informed that Kansas authorities had revoked her medical license. A judge ruled that she did not perform adequate mental health examinations of 11 abortion patients. The prosecution said that Neuhaus was a “threat to any future patients she might have.”

There comes a time when a human being has to either face evil or admit to allowing it. Abortion is legal in the United States, but it should not be celebrated or used as a political tool. Viable babies are human beings. If they could talk, they would tell Williams and other pro-choice zealots that their lives should not be marginalized by someone who thinks she’s the boss.

Bill O’Reilly is host of the Fox News show “The O’Reilly Factor.”