Donald Trump took to Twitter — surprise! — Saturday to slam U.S. Rep. John Lewis, the Georgia Democrat, for saying that he planned to skip Trump’s upcoming inauguration because he doesn’t consider Trump to be a “legitimate president.”

However ill-considered Trump felt Lewis’s comments to be, the president-elect might have done well to avoid hitting back on this particular weekend. Lewis is an icon of the civil rights movement, Martin Luther King Jr. Day was Monday, and Lewis famously marched with King into Selma, Alabama, in 1965, enduring a brutal police beating and a cracked skull along the way.

Instead, of course, Trump tweeted that Lewis “should spend more time on fixing and helping his district, which is in horrible shape and is falling apart (not to mention crime infested) rather than falsely complaining about the election results.” After a breather — and a wave of social media criticism of his remarks — Trump jumped back into the ring several hours later, tweeting that “John Lewis should focus on the burning and crime infested inner-cities of the U.S.”

On the facts alone, Trump is running ragged here. During his campaign and now in his swipes at Lewis, he has warned of frightening inner-city crime rates which he has said are reaching “record levels.” Yet despite a recent, two-year jump in urban crime, rates have been plunging for years. Even homicide-plagued cities such as Chicago have crime rates well below those of the early 1990s. (Crime statistics can be complex to parse; 2016 figures haven’t arrived yet, and a definition for “inner-city crime” doesn’t exist).

Lewis’s congressional district is in the heart of metropolitan Atlanta, where the overall crime rate is also historically down (homicides have spiked in the last two years). Lewis’s district is hardly falling apart. It includes a major airport, several higher-education institutions, Fortune 500 headquarters for Coca Cola Co. and others, some poor neighborhoods and a diverse population.

On Sunday morning, the Atlanta Journal-Constitution published a front-page headline in big block letters: “ATLANTA TO TRUMP: WRONG.” Local business owners concurred, saying that things are “on the upswing” for them, and one of the Journal-Constitution’s columnists, Jim Galloway, took Trump to account under the headline: “Dear Donald Trump: Scarlett O’Hara and Rhett Butler Have Retired.”

More than facts are askance in Trumplandia. The president-elect is insulted because Lewis questioned the legitimacy of his presidency, but Trump spent years railing against Barack Obama’s citizenship and legitimacy to be president as part of the birther movement.

Lewis and Trump also have starkly divergent personal histories. Lewis, 76, was born in Alabama to sharecroppers descended from slaves. Trump, 70, was born in New York to a wealthy real estate developer.

When both men were young adults in the 1960s, they developed very different notions of civic and personal responsibility as well. While Lewis put his life on the line advocating civil rights, Trump attended Fordham University and then the University of Pennsylvania, where he arranged five draft deferments so he wouldn’t have to fight in the Vietnam War.

Trump’s fifth deferment was for medical reasons: a bone spur in one of his feet (Trump has occasionally had trouble remembering which foot was afflicted; his representatives say both of his feet had the malady, which derives from excess calcium creating a small, talon-like extension from one or both of Trump’s heels). Though the spurs kept Trump off the battlefield, they didn’t prevent him from being a well-regarded teen athlete who excelled in football and basketball and was so proficient on the base paths that his high-school coach thought he could become a professional baseball player. Trump remains an avid and skillful golfer.

In 1973, five years after Trump joined his father’s business and two years after he took control of what was then known as Trump Management, the Justice Department sued the Trumps for violating the Fair Housing Act by discriminating in their developments against renters of color. The suit, detailed at length by Wayne Barrett in his 1992 Trump biography, “Trump: The Greatest Show on Earth,” was settled in 1975. The Trumps settled the suit without acknowledging any wrongdoing, agreed not to discriminate against buyers or renters in the future and also agreed to take out ads alerting minorities to available housing at Trump properties.

Equal access to housing is an issue John Lewis has spent most of his life supporting, and it was one of Martin Luther King Jr.’s signature causes when he marched in cities like Chicago. Congress passed the Fair Housing Act a week after King was assassinated in 1968.

So as we celebrate MLK Day, and as Donald Trump moves closer to his Inauguration Day, both events might offer the president-elect a chance to reflect upon the immense power he is about to assume and how best to wield it.

You have many battles ahead of you, President-elect Trump. Please pick the right ones.

Timothy L. O’Brien is the executive editor of Bloomberg Gadfly and Bloomberg View.