I was taken by surprise in March 2013 when Senator Rob Portman (R-OH) announced that he now favored same-sex marriage. I understood how he might have arrived at his change of heart. After all, not long before he had found out that his son is gay. That’s something we share in common. I too have a gay son.

But after that, our stories diverge: I remain unable to call two men or two women in a committed relationship a “marriage.” And there’s a second way I differ from Senator Portman: like my son, I identify as gay.

What makes this intriguing is that, until a few years ago, I was outspoken in support of same-sex marriage. Senator Portman’s about-face left me scratching my head for a long time. How did the two of us start at opposite ends of the spectrum and then end up landing in each other’s former position? Somewhere along the line, our paths had crisscrossed, just as mine presumably had with President Obama, Institute for American Values president David Blankenhorn, and even former Vice President Dick Cheney (whose daughter, Mary, is a lesbian).

In early 2012, I spent a few days in Annapolis, meeting with as many of my home-state legislators as I could, hoping to bolster their resolve to oppose a pending same-sex marriage bill. With the Maryland House vote looming, I stood outside a legislator’s door—stunned—after word got to me that Dick Cheney was calling wobbly Republican Delegates, seeking their support for the measure. A couple days later, the bill passed by a thin margin with the help of two Republican votes.

Things soon turned stranger. When a national brouhaha erupted over Chick-fil-A president Dan Cathy’s stated opposition to same-sex marriage, Boston Mayor Thomas Menino responded, “There is no place for discrimination on Boston’s Freedom Trail and no place for your company alongside it.” I quickly realized that if Mayor Menino’s words were taken at face value, despite the fact that I am gay, I too would be banned in Boston, while its Democratic mayor would happily roll out the red carpet for former Vice President Cheney, normally a toweringly adversarial figure.

Was there something wrong with me? Why did I seem to be swimming upstream, against the current, while all these others were floating by with such ease, buoyed by a pleasant tide of media adulation?

Natural Law: Lessons from the Road Runner and Wile E. Coyote

In his “coming out” letter in The Columbus Dispatch, Senator Portman said:

I wrestled with how to reconcile my Christian faith with my desire for Will to have the same opportunities to pursue happiness and fulfillment as his brother and sister. Ultimately, it came down to the Bible’s overarching themes of love and compassion and my belief that we are all children of God.

I too believe that we are all children of God, but still, I can’t make myself come to the same conclusion as Senator Portman, no matter how hard I try. For while each of us is a child of God, deserving of love, respect, and dignity, I can no longer brush aside the reality of natural law, and in particular, complementarity.

For many, the term natural law may hold little or no meaning, but its reality is foreign to no one. Natural law respects human nature exactly as it exists, and is clearly evident through observation and reason. As citizens of the United States of America, we benefit from the recognition of natural law day in and day out:

We hold these truths to be self-evident, that all men are created equal, that they are endowed by their Creator with certain unalienable Rights, that among these are Life, Liberty and the pursuit of Happiness.

In the same way, complementarity is a truth that is self-evident. Nature clearly presents the complementarity of man and woman—a quality that is nonexistent in same-sex relationships, where mirror imagery is instead the dominant characteristic. Activists yell loudly to suppress natural law from both our consciousness and public debate, but they will never succeed. They can only temporarily distract. Reason and nature make the erasure of natural law utterly impossible.

Louisiana District Judge Martin Feldman’s recent decision in Robicheaux v. Caldwell describes the cascade of media, celebrity, judicial, and legislative support for the notion of same-sex marriage as “a pageant of empathy; decisions impelled by a response of innate pathos.” Such empathy and pathos undoubtedly emanate from the best of intentions and good will, but are being tempered by neither reason nor law.

Here’s the thing: I don’t actually oppose same-sex marriage, although I continue to use that terminology as a sort of inexact shorthand. For me, same-sex marriage has simply been rendered a non-issue, because I recognize the irrefutable nature and irresistible truth of complementarity. Assenting to self-evident truths has a way of shining a bright light on the fog of relativism, including the notion of genderless marriage. What was once a viable option for me evaporated in that bright sunlight, along with any lingering justifying arguments in my mind. All that remains is the exquisite, undeniable truth of complementarity.

A few years ago, as I did an honest assessment of my life, I had to admit that two men (or two women) in a relationship is not exactly the same as a man and a woman. I surprised myself with my conclusion. But there it was. The truth was undeniable. At the same time, I concluded that children need and deserve to be raised by both their mother and their father—not two dads or two moms—but Mom and Dad together, in the same house. That truth was so powerful that I was compelled, with the help of my ex-wife, to pull our marriage and family back together again. That was four wonderful years ago.

Like Newton’s law of gravity, natural law can’t be defied or ignored, at least not for long. We deny or disregard the significance of complementarity at our own peril, for the consequences of our denial will likely be staggering. Remember the Road Runner cartoon on Saturday mornings? Wile E. Coyote is able to resist gravity for a few seconds as he speeds off the edge of a cliff, unable to stop or turn as agilely as the Road Runner. He lingers in the air for a few seconds, but gravity always wins, sending poor Wile E. plummeting to the canyon floor, a thousand feet below.

While it may be funny when something like that happens to a cartoon coyote, it’s tragic when children deprived from birth of either their mom or their dad eventually find their lives in emotional free fall.

Like gravity itself, the logic and wisdom of complementarity are inescapable. Like nature, complementarity’s simple organic beauty and elegance are undeniably profound. And while the Bible’s themes of love and compassion are indeed overarching, unconditional love does not require that we pretend that all relationships are precisely equal, or that moms or dads are expendable for children. Kids not only do better when raised by both mom and dad, they absolutely deserve to be. Unfortunately, it’s easier to pretend at the expense of an infant or a child than it is to speak truthfully to other adults.

I wonder if Senator Portman, before changing his mind, thought beyond his son to his future motherless grandchildren? This is a very real long-term unintended consequence.

Speaking to a world which “has not given one moment’s thought to the ethical merit of third party reproduction,” Alana Newman, founder of the Anonymous Us Project, said:

Even though you hear again and again that these processes work to “make people happy,” please understand that they do not in fact make people happy. They only delay or transfer pain.

Turning a blind eye to natural law and, in particular, to complementarity initially appears compassionate, even salvific. But it comes with an enormous price tag—an unforgivable debt—which none of us can afford to pay.