When I was a child, many white Americans, and most of them in the South, considered Martin Luther King Jr. and other civil rights activists to be radicals and trouble-makers. Some even called them "communists."

Almost everyone now considers them heroes. Ideas about racial equality and justice that were then controversial are now common sense.

Segregationist leaders such as George Wallace, Lester Maddox and Orval Faubus are now remembered with contempt, when they are remembered at all. We pity the average people who enabled the bigots, either with their actions or their silence.

On Monday, we mark the 27th annual holiday honoring King, as well as the second inauguration of the nation's first president of African descent. Looking back, it is amazing how much changed in so short a time. Racism still exists, to be sure, but it is no longer acceptable in mainstream society.

It makes me wonder: What controversial ideas today will seem like common sense in just a few years?

The first that comes to mind is gay rights. It is today's most controversial civil rights issue, yet the nation has clearly turned the corner. You can tell it the same way you could tell by the early 1960s that we had turned the corner of black civil rights. The groundswell of support wasn't just coming from the victims of discrimination, but from others who realized it was wrong and found the courage to say so.

If there has been a consistent theme of social progress during my lifetime, it is this: discrimination against any group of people because of who they are is un-American.

We saw an example of that last week when the small Perry County town of Vicco became the fourth municipality in Kentucky to ban discrimination against gays, joining Lexington, Louisville and Covington. Vicco officials said they weren't endorsing homosexuality; they just thought discrimination was wrong.

Most opposition to gay rights comes from religious conservatives. During King's lifetime, many white Christians found Biblical justification for segregation and discrimination, just as their great-grandfathers had for slavery. Everyone is entitled to their religious beliefs. What is problematic is when they try to impose them on others.

Wendell Berry, the renowned Kentucky writer and lifelong Baptist, made that point and many others to Baptist ministers meeting at Georgetown College on Jan. 11. Coverage of his talk has attracted a lot of attention. (Click here to read more about it.)

When I think of other controversial issues that will seem like no-brainers in a few years, the reasons for our clouded judgment have more to do with economics than religion.

Kentuckians' disregard for the environment reminds me of our willful ignorance about the health and social costs of tobacco just two or three decades ago. Only after the price-support system that made tobacco an economic mainstay of family farms was abolished did we stop trying to deny the obvious and defend the indefensible.

More than 30 local governments in Kentucky now have public smoking bans, and some legislators are pushing for a statewide version to curb soaring health-care costs. Restricting smoking in most public places is now common sense, yet it would have been unthinkable in Kentucky a generation ago.

Sit back for a moment and try to image conventional wisdom a few years from now. For one thing, I think, discrimination based on sexual orientation will be as unacceptable then as discrimination based on race, gender or national origin is now.

I also can imagine hearing comments like these:

Why did people back then allow the beauty and future economic viability of Eastern Kentucky's mountains to be destroyed just so coal companies could extract the last measure of profit in return for a declining number of short-term jobs?

How could people back then have denied the scientific consensus about climate change and refused to act when the signs — melting glaciers, the increasing frequency of killer storms and droughts, year after year of record-high temperatures — were so obvious?

What were they thinking?

As we honor civil rights heroes Monday, and pity the bigots and their enablers, let us also give some thought to the future. Who will people honor then, and who will they pity?

And ask yourself: which side of history will I be on?