This week, we are witnessing change.

On Friday, Jan. 20, a new president will be inaugurated. Donald J. Trump, the billionaire businessman who has never held elective office and is so guided by impulse that he rarely holds his tongue, will become the 45th president.

As President Obama, an intelligent, grounded and measured man, turns over the reins of power and leadership during official ceremonies outside the U.S. Capitol, we will watch as the nation’s first African-American president heads off into history.

Already, the regressive elements in Congress are hard at work trying to make President Obama’s advances of the last eight years disappear like a page torn from a history book.

In a marathon session last week that ended shortly after 1 a.m., Senate Republicans launched the latest salvo in their war to dismantle President Obama’s landmark health care law by approving a budget blueprint they call the Obamacare “repeal resolution.” With no clear plans to replace the health insurance program, the 51-48 party-line vote was a beginning death knell of the progress made during the Obama years. The House of Representatives followed suit last Friday.

“This resolution will set the stage for true legislative relief from Obamacare that Americans have long demanded while ensuring a stable transition,” Senate Budget Chairman Mike Enzi of Wyoming said, following the repeal vote. “The Obamacare bridge is collapsing and we’re sending in a rescue team.”

Unfortunately, many Americans who supported the strident but empty Mr. Trump now are realizing their mistake when the health insurance program they have come to rely on to cover pre-existing conditions and expensive medical tests and procedures will be gone. There will be no team — not even a Saint Bernard — to rescue them.

On Sunday, thousands of people joined rallies in cities across the nation in support of Obamacare, including one in Richmond that drew nearly 1,000 people. More than 20 million who gained health insurance coverage under Obamacare since 2010 stand to be impacted by the Republican rollback.

So when this week began with the official Martin Luther King Jr. Holiday and an eye toward what awaits on Friday, the message of hope that typically comes with Dr. King’s words was tinged with weary sadness.

“Change does not roll in on the wheels of inevitability, but comes through continuous struggle,” Dr. King wrote. “And so we must straighten our backs and work for our freedom. A man can’t ride you unless your back is bent.”

We applaud Rep. John Lewis of Georgia and the more than 50 members of the U.S. House of Representatives who are standing tall in their decision to boycott Mr. Trump’s inauguration.

For Rep. Lewis, a civil rights icon who worked alongside Dr. King and learned hard and bloody lessons in combating racism throughout the South in the 1960s, the choice was simple:

“I don’t see this president-elect as a legitimate president,” the 76-year-old Democrat told NBC’s “Meet the Press” on Sunday. “I think the Russians participated in helping this man get elected. And they helped destroy the candidacy of Hillary Clinton.”

It will be the second inauguration he has missed since being seated in Congress in 1986. He skipped President George W. Bush’s inauguration in 2001 in protest.

“You cannot be at home with something that you feel is wrong,” he said. “It’s not right.”

Since then, the president-elect has gone after Rep. Lewis, criticizing him and his district via Twitter messages.

Many of those standing with Rep. Lewis are members of the Congressional Black Caucus, including Rep. Keith Ellison of Minnesota, the first Muslim to serve in the House of Representatives. Virginia lawmakers who have announced plans to boycott the inauguration include freshman Rep. A. Donald McEachin, who represents Richmond, and Rep. Don Beyer of Northern Virginia.

In a statement issued Wednesday, Rep. McEachin said his train ticket to D.C. would go unused this weekend. He said Mr. Trump’s rant about Rep. Lewis was the deciding factor.

“I’ve never seen a campaign that was based on hatred. He insults and denigrates a man who is a true hero,” he said.

Rep. Beyer, a Democrat who served as lieutenant governor under L. Douglas Wilder, the nation’s first elected African-American governor, said he treasures the peaceful transfer of power and respects the constitutional prerogatives of the presidency.

“But I will not be part of normalizing or legitimizing a man whose election may well have depended on the malicious foreign interference of Russia’s leaders, a person who lies profusely and without apology, who mimics the disabilities of others, who insults anyone who dares disagree with him, who would demonize an entire spiritual tradition and who has demonstrated again and again a profound disrespect for women. His values and his actions are the antitheses of those I hold dear. It would be the height of hypocrisy for me to pretend to be part of this inaugural celebration.”

We ask, what is there to celebrate? What can Mr. Trump possibly say in his inaugural speech?

To bind the nation’s wounds, he could apologize to the American people to start with. He has alienated so many people by his words and his actions that his approval rating is the lowest of any incoming president in the past 40 years.

We join with Rep. Lewis, Rep. McEachin, Rep. Beyer and the others who will use the inauguration to send a clear message to Mr. Trump and those Republicans and Democrats who are listening that we cannot celebrate the bigoted and divisive agenda Mr. Trump campaigned on and continues to drive long after the election.

How can we celebrate someone who denigrates women, seeks to ban Muslims from coming into the country, crows about building a wall on the U.S. border to keep Mexicans and other immigrants out, nominates for U.S. attorney general someone who has a record opposing civil rights and voting rights, appoints as his chief strategist a man who is a KKK sympathizer, and who is focused on trying to take health insurance away from millions of people?

“Injustice anywhere is a threat to justice everywhere. We are caught in an inescapable network of mutuality, tied in a single garment of destiny. Whatever affects one directly, affects all indirectly,” Dr. King said.

The policies put forth by Mr. Trump on the campaign trail are harmful to this nation. That will not change when he takes office.

His first test as president will be how he deals with the people who boycott his inauguration and how he handles the hordes of protesters who will be in Washington on Friday and the 200,000-plus expected for the Women’s March on Saturday, Jan. 21.

Will he trample on their First Amendment rights of freedom of speech and assembly to march for the poor, the marginalized and the most vulnerable in the nation under a new Trump administration?

We will see.

We urge our readers and people everywhere to raise their voice this weekend and throughout the coming days and years of the Trump administration.

Speak up to combat wrongs. Speak up for what is right.

When history is written about the day surrounding the inauguration of the nation’s 45th president, let it show that you didn’t remain silent.

“The ultimate measure of a man is not where he stands in moments of convenience and comfort, but where he stands at times of challenge and controversy,” Dr. King said.

Those moments are now.