(CNN) His opponent calls Rev. Raphael Warnock an unpatriotic radical who celebrated the "hatred" of a fiery Black pastor who, in a notorious sermon, once declared that God damned America.
But there's another, little-known pastor who inspired Warnock, the Democratic nominee for Georgia's upcoming Senate runoff election. Critics never seem to mention him, but this pastor was also radical in his own way.
This pastor was a Black World War II veteran who flew an American flag in front of his house, hung portraits of American presidents on his walls and led a church that recited the pledge of allegiance before every Sunday morning worship.
This man was Warnock's father, the late Rev. Jonathan Warnock.
He was a Pentecostal pastor who salvaged abandoned cars while raising 12 kids in a public housing project with his wife, the Rev. Verlene Warnock. A compact, wiry man, he worked so hard hauling hunks of metal that he often closed his eyes while eating dinner because he was so exhausted.
"The man who saw the value in a junk car that another person had thrown away during the week preached to people who themselves felt discarded," Warnock says.
Warnock says those who attempt to link him with an angry Black pastor's sermon confuse moral outrage with hatred. When people call him an anti-American radical, he responds in part by citing his father's military service.
But the impact of the elder Warnock on his son's ministry and politics is more profound than most people realize
Jonathan Warnock was no radical in the sense that he advocated a violent revolution or a massive redistribution of wealth. But as these two stories from his life illustrate, he broke sharply from tradition in several key ways.
Jonathan Warnock joined the US Army during World War II. Like many veterans, he hoped that life would improve for him when he returned from the war. He quickly learned otherwise.
After the war ended, he boarded a public bus in his Army uniform to return home to Savannah, Georgia. As the bus took on more passengers during the trip, the driver turned to Warnock.
"The bus driver asked him to remove himself to another seat so that a teenage White boy could sit down," says Valencia Warnock King, one of the late pastor's daughters.
One of the ironies of that period is that Black veterans sometimes faced more danger walking around in their uniforms at home than abroad. Black veterans returning from combat after both World Wars were routinely ordered to move off sidewalks for White pedestrians and shunted to the "colored" sections of trains or buses. Some were beaten or lynched for wearing their uniform in public.
The elder Warnock moved from his bus seat, but he never forgot the episode. He salvaged a "For Whites Only" sign and kept the Jim Crow relic in his house. And he told the story of that bus ride to his children repeatedly as the years passed, says King, a nonprofit consultant.
"He said we gotta address these things because we love this country and we ought to fight for things that are right," she says.
Yet Warnock also flew an American flag at his house and hung another American flag behind his church pulpit. He decorated his walls with portraits of Abraham Lincoln and John F. Kennedy. Every November, when Veteran's Day rolled around, he told his children how proud he was to serve his country during the war.
"My dad loved America," Warnock says. "He took the long view. He understood that we were in the process of trying to build a more perfect union. He was not unaware of the contradictions of race. He was born in 1917, a Black man in the Jim Crow South. But by the time my sister and I had come along, he had also seen the arc of change in our country, so he knew what was possible."
The elder Warnock's love of country, though, was not the traditional, "love it or leave it" patriotism that was popular at the time. He, like many Black people, had to find a way to love a country that didn't always love him back.
To do so, he and others adopted a patriotism that defined America as great not just because of what it was, but because of what it could become. It's the kind of patriotism that the poet Langston Hughes invoked in 1935 when he celebrated America as "The land that never has been yet -- And yet must be -- the land where every man is free." It's the kind of patriotism that insists that protests are just as patriotic as standing for the Pledge of Allegiance.
It's a radically different way of loving one's country.
President Obama spoke about it in what many consider his finest speech, his 2015 address in Selma, Alabama, when he asked, "What greater form of patriotism is there than the belief that America is not yet finished, that we are strong enough to be self-critical?"
Warnock attended Obama's first inauguration in 2009 and remembers a moment from that day when his father's belief in America's promise seemed validated. He had wanted to bring his father to Washington for the event, but his dad was too frail at the time.
"And so while the inauguration was going on, I called him on the phone and we shared that moment," Warnock says. "He was so proud of Obama. He was so proud of America."
Warnock says his father's belief in America taught him to not give in to bitterness or hatred.
"Considering all he had been through, I've always felt that my generation had no reason to give up."
The elder Warnock was a Pentecostal pastor, a tradition which tends to emphasize what some call the "baptism of the Holy Spirit": speaking in tongues, healings and prophecies. Pentecostal churches tend to teach that the Bible is infallible.
But Jonathan Warnock was different. His daughter, King, recalls an impromptu Bible lesson he gave to his children during Easter one year. He challenged the traditional Easter message -- that Jesus died because of mankind's sins. Did he also die because he was a revolutionary who sided with the poor?
His daughter says he didn't think pastors should confine their concerns to saving souls -- they should also preach about social justice.
"He used to say, 'We can't be so heavenly bound that we're no earthly good,'" King says today.
Jonathan Warnock also broke religious convention in another way. Many Pentecostal churches do not ordain women as pastors. They quote the Bible to justify excluding women from the pulpit.
But the elder Warnock didn't have any problem with his wife, Verlene, being a Pentecostal pastor. It was a bold position to take -- then and now.
"I'm very proud of the fact that my dad, given the generation he was part of, was fully supportive of my mother in ministry," Warnock says. "That's still not true of some pastors today. They will argue and cite scripture for their justification for denying women to the ministry."
Warnock says his father was the first to teach him the importance of preaching about social justice.
"He didn't have formal seminary training, but he had a critical and thoughtful mind," Warnock says. "He often challenged traditional views on scripture and he certainly didn't have much patience with an other-worldly religion that was an escape from a present reality."
Republicans have attacked the younger Warnock's political views, which he says is grounded in his faith. One critic suggested his brand of Christianity may be too radical for Georgia voters. His opponent, GOP Sen. Kelly Loeffler, has accused him of defending what she calls "the hatred" in the infamous "God damn America" sermon delivered in 2003 by the Rev. Jeremiah Wright Jr., the former pastor of the Chicago church that President Obama once attended.
In response, Warnock has said people often confuse Black preachers' moral outrage with hatred and that he has spent his "whole career standing up against bigotry."
But in some ways Warnock's critics are right -- his faith is radical. So was his father's. So was that of Warnock's predecessor at Ebenezer, the Rev. Martin Luther King Jr.
Virtually every Black pastor in the public spotlight who has preached about social justice has been labeled a radical. King was called a radical, a communist and anti-American for denouncing the Vietnam War. The Rev. Billy Graham refused to participate in the 1963 March on Washington and often criticized King for his political activism.
The attacks on Warnock's faith underscore the fact that there have long been competing visions of Christianity in America: one embodied by King and the other by Graham. One religious tradition emphasizes changing hearts and individual sin. It's the kind of Christianity that many White ministers once used to justify slavery and segregation.
But many Black preachers told worshipers that personal piety wasn't enough -- unjust laws and institutions must change as well. They talked about social justice, not just getting souls to heaven.
This social justice message is seen as so radical that even some Black churches shun it. King, for example, was driven out of the largest Black Baptist organization because some of its leaders opposed his nonviolent civil disobedience tactics.
The difference between these two visions of Christianity was memorably captured by Dom Helder Camara, a Brazilian bishop, who once said:
"When I give food to the poor, they call me a saint. When I asked why the poor are hungry, they call me a communist."
Warnock says social justice is integral to his politics and faith. Many of his policy positions, such as supporting a living wage and the full Medicaid expansion of Obamacare in Georgia, spring from his faith -- and that of his father.
"I'm a Matthew 25 Christian, and everything that I have done derives from my faith," he says. "My activism and advocacy are connected to my belief that the gospel is at heart good news to the poor. It is setting the captives free. It is the affirmation that all of us have within us a spark of the divine... I've been so engaged in social justice issues because I believe that ought to play itself out in our public policy."
The preacher who first instilled those concerns in him was not King but his father, he says.
"I'll find myself going to a text and I'll remember what he said about the text and how it inspired me, even with all of my formal training," he says. "I still remember some of those sermons. I've preached my own versions of those stories."
The elder Warnock had little doubt about what preaching tradition his son stood in. He watched his son graduate from Morehouse College, King's alma mater. And on Father's Day in 2005, he got a call from his son with some good news. He had been selected to become the senior pastor of Ebenezer, King's church in Atlanta.
Warnock's sister, Valencia King, still remembers her father's reaction that day.
"He cried," she says.
Her family's turn to cry came five years later. Jonathan Warnock was taken to the hospital with pneumonia and died in September 2010 after complications set in. He was 93. Warnock was at his father's side as doctors disconnected him from life support. He stood for a while and stared at his father's body in silence.
He then walked out to his family in the waiting room. King, his sister, recalls what he said: "The Lord has spoken."
Soon, the voters of Georgia will speak. If Warnock wins, he would be the first Black senator elected from Georgia. The race has attracted national attention, in part because it could determine which party controls the Senate.
"I know he would be extremely proud of this moment," Warnock says of his father. "I wish he were here to witness it, but as a person of faith, there is a sense that I feel like he is here."
Warnock's potential election could also offer a more personal form of vindication.
The son of a Black veteran who had to give up his seat on a bus to a White teenager would take his own seat in the US Senate. And a Black pastor from Ebenezer who is labeled a radical could again help shape the nation.