Editor’s note: This article first appeared at The Guardian.

With the Supreme Court giving a major boost to gay marriage, liberals face fewer impediments to their relentless push for fatherless (and motherless) families.

Of course, it wasn’t always this way. In a speech for Father’s Day 2008, Barack Obama was emphatic in championing fatherhood: “We know the statistics – that children who grow up without a father are five times more likely to live in poverty and commit crime; nine times more likely to drop out of schools and 20 times more likely to end up in prison. They are more likely to have behavioral problems, or run away from home, or become teenage parents themselves. And the foundations of our community are weaker because of it.”

Obama added: “Of all the rocks upon which we build our lives … family is the most important. And we are called to recognize and honor how critical every father is to that foundation.” If “we are honest with ourselves,” said Obama, “we’ll admit that … too many fathers” are missing – they are “missing from too many lives and too many homes.

Obama summed up: "We need fathers.”

I couldn’t agree more. In fact, as a conservative, I don’t know a single conservative who would disagree with any of this – alas, a rare moment of complete agreement with Barack Obama. For that matter, I don’t know any liberals who would disagree.

So, with that being the case, why are President Obama and liberals suddenly pushing unrelenting for fatherless families – or, more specifically, for a new form of American family that is fatherless?

The answer, of course, is gay marriage. With their sudden embrace of gay marriage, a massive shift not only within America, American culture, and human civilization, but also within the Democratic Party, liberals/progressives nationwide are – whether they realize it or not – simultaneously advocating a redefinition of family that embraces fatherless families. Think about it: married female-female parents will be households without dads.

In so doing, liberals are shattering a rare, precious consensus that they had nurtured with conservatives. There are few things that liberals and conservatives agree upon, but one of them was the crucial importance of children being raised in a home with a dad and a mom.

In his 1984 Father’s Day proclamation, President Ronald Reagan described fathers as “beacons” of “strength and well-being,” of “leadership and direction.” They give their children guidance and teach them “integrity, truth, and humility.” “Every father rises to his tallest stature as he selflessly cares for his family, his wife, and his children,” said Reagan.

Liberals from Walter Mondale and Daniel Patrick Moynihan to the pages of The New Republic and New York Times emphatically agreed with Reagan. A decade later, such sentiments were consistently reinforced by Democratic President Bill Clinton, who understood the toll delivered by fatherless homes. Groups like the National Fatherhood Initiative popped up, creating wonderful ad campaigns reminding Americans of something that societies long deemed indispensable: kids need dads. Sons need dads. Daughters need dads. Families need dads.

That principle remains unchanged. What has changed, however, is liberals/progressives fierce acceptance and advancement of gay marriage. In this rapid push, they are jettisoning this national consensus on fathers, demanding a form of parenting that excludes fathers. As for those who disagree with their new paradigm, they are derided as cruel, thoughtless bigots, with no possible legitimate reason for their unenlightened position.

Actually, what today’s liberals are advocating is far more radical than that. They are pushing not only for fatherless families but also, conversely, motherless families. Think about it: married male-male parents (the other half of gay marriage) will be households without moms.

Everyone reading my words knows that mothers are utterly irreplaceable. That’s a statement of the obvious. I’m incapable of doing what my wife does. Fathers raising kids without their mother because of divorce, death, or some other unfortunate circumstance, know what I’m talking about. Why would anyone, let alone a country or culture, want to open the door for a reconstitution of “parenthood” and “family” that, by literal definition, excludes mothers?

To be sure, we know why liberals are doing this. Again, they are doing this in the name of gay rights.

Yet, supporting gay rights, and the right of gay people not to be discriminated against, should not automatically mean supporting the literal redefinition of marriage. Why must tolerance mean the redefinition of something as ancient and stable as marriage between one man and one woman?

The original push for gay rights was about stopping discrimination. Gays should not be persecuted, denied benefits, fired because of their sexual orientation. We all support that. But like with many other things, liberals in their zeal for whatever new “rights” are pushing too far, without pausing to carefully consider the impact. Their furious dash to redefine marriage in the name of gay rights has innumerable consequences that they have not begun to try to contemplate; that includes a new marriage/parenthood paradigm that repudiates their onetime insistence on father-based families, and even mother-based families.

Liberals always appeal to our emotions regarding children: What about the children? Well, yes, what about the children?

As Barack Obama said in 2008, if we’re honest with ourselves, we’ll admit that children need fathers. Yes, if we’re honest. They need fathers, and mothers. Dr. Paul Kengor is professor of political science at Grove City College, executive director of The Center for Vision & Values, and New York Times best-selling author of the book, “The Communist: Frank Marshall Davis, The Untold Story of Barack Obama’s Mentor.” His other books include “The Crusader: Ronald Reagan and the Fall of Communism” and “Dupes: How America’s Adversaries Have Manipulated Progressives for a Century.”