Here's a 21st-century truism for you: We are a tolerantly intolerant people.

Sounds odd, but think about it. We are too often intolerant when it comes to the race, ethnicity, culture, economic status, political beliefs, gender, even religion, of others. And that's just for starters.

Yet in those differences we continue to live, mostly together, on a small and rocky and mostly wet place we call earth. Those differences bring about war, hatred, discrimination. Those differences create refugees, victims, oppressors and the oppressed.

Despite that perhaps painful truth, we have created in the United States the most diverse and culturally inclusive nation on earth. It is so different that other nations wonder how we do it. Sometimes they wonder appreciatively, and sometimes they wonder if we'll survive. If we're honest, sometimes we wonder ourselves. Nevertheless, that diversity is at the root of all that is America.

But all that diversity and inclusivity hasn't happened without a great deal of tolerance and intolerance, acceptance and bigotry.

Was there intolerance when the great influx of Irish Catholics hit our shores in the middle of the 19th century? You bet! Many thousands of those immigrants arrived in the Midwest to dig the ill-fated Illinois and Michigan Canal. The Irish and their "papist" religion were neither wanted nor accepted by America's Protestant majority. There was intolerance, even violence. What happened? Chicago became one of the America's greatest Catholic cities.

Neither is the Irish experience unique. Other ethnicities and races experienced that same cycle of intolerance, tolerance and acceptance. It has been sadly slower and more grudging for some. Black Americans find acceptance still often illusionary. It's still an ongoing story for America's Hispanics, whose numbers and faith enrich our parishes and communities.

Intolerance is hardly a modern invention. Cruel wars have been fought over prejudice. The terrible Thirty Years' War, which slew millions in the early and mid-17th century, pitted Catholics against other Christian denominations. Bias against Jews was a huge part of World War II and the fate of blacks was at the core of the Civil War and the century of Jim Crow laws that followed.

Wars -- terrorism, too -- continue because of bigotry and intolerance.

Even Jesus knew about prejudice. The Romans looked down on the Jews. The Jews looked down on the Samaritans. The rich looked down on the poor. And everyone looked down on the slaves.

Tolerance and intolerance.

We Catholics aren't exactly slouches when it comes to intolerance. There was that little thing called the Inquisition. And we sometimes continue to be less than welcoming of others, especially Jews and Muslims. That intolerance exists on both sides. Anti-Catholic prejudice, which has been in the news recently, has sometimes been called the "last acceptable bias." It's not, of course.

So, all that being said, what do we do about tolerance? About intolerance? Understanding how it begins is a start. An apocryphal story, which I couldn't confirm, goes like this: There's a sign on a school in Belfast, Northern Ireland, that speaks volumes about the violent intolerance between Catholics and Protestants that affected that area for decades.

It reads: "If you were born where I was born and were taught the things that I was taught, you might believe the way I believe."

Apocryphal or not, it's a powerful painful lesson because it acknowledges the roots of intolerance. We all have a history, a bias. Intolerance is homegrown; we bring it with us wherever we go.

You'd think we'd know better, recalling the scriptural command to love your neighbor as yourself. But too often, we don't. So this is a reminder: Intolerance is dehumanizing. Tolerance, on the other hand, is godly.