BRUNSWICK, Ga. - Hundreds of pastors both rallied and prayed last week outside the trial of three white men charged in the killing of Ahmaud Arbery. They gathered in response to a defense lawyer’s bid to keep Black ministers out of the courtroom.

As testimony resumed inside the Glynn County, Ga., courthouse, with its four huge columns, arched windows and shaded lawn, a group of mostly Black ministers gathered outside on Nov.18—as sea of dark suits and white collars.

Many carried signs reading, “Black pastors matter,” and some wore buttons with Mr. Arbery’s picture and the hashtag they were using for the case, “#Justice For Ahmaud.” A vendor sold T-shirt s under one tent while a woman under another offered water and snacks and asked people to put donations in a pickle jar.

The Rev. Al Sharpton, head of the National Action Network, announced the rally after a defense attorney intensified frustrations in the coastal Georgia community of Brunswick when he said he didn’t want “any more Black pastors” sitting in the courtroom.

After the Rev. Jesse Jackson, Rev. Sharpton and others sat with Mr. Arbery’s family in court, defense attorney Kevin Gough asked the judge on Nov. 11 to kick out the pastors, saying civil rights icons could influence the jury.

“We don’t want any more Black pastors coming in here ... sitting with the victim’s family, trying to influence the jurors in this case,” Mr. Gough said. “If a bunch of folks came in here dressed like Colonel Sanders with white masks sitting in the back ... ” Mr. Gough said before Superior Court Judge Timothy Walmsley cut him off.

The attorneys for the other two men on trial did not join Mr. Gough.

Judge Timothy Walmsley called the request against the Black pastors “reprehensible” because, in the United States, trials and courtrooms are open for all outside of pandemic concerns, and the pastors had followed those rules.

“The court is not going to single out any particular individual or group of individuals as not being allowed into his courtroom as a member of the public,” Judge Walmsley told Mr. Gough. “If there is a disruption, you’re welcome to call that to my attention.”

Rev. Sharpton said he started gathering dozens of Black pastors to pray outside the courthouse Nov. 18 with lawyers representing Mr. Arbery’s family.

“They tried to ban one. We’re coming back with a hundred,” Rev. Sharpton said.

As the crowd grew outside last week, Rev. Jackson once again joined Mr. Arbery’s family in the courtroom. Criticizing the failed attempt to keep Black pas- tors out of court, Rev. Sharpton told the rally that no one had questioned who is sitting with the defendants’ families.

“No lawyer can knock us out. Because no matter where you are, God is there,“ he said. “We are going to keep coming until we get justice.”

Martin Luther King III, son of slain civil rights leader Dr. Martin Luther King Jr., addressed the throng saying, “It only takes a few good women and men to bring change.”

Prayer has been a key to helping Black people through centuries of slavery, violence and discrimination in America, said Mr. Arbery’s father, Marcus Arbery. “That’s all we lived on. That’s all we had was prayer. What did our great-grandmothers depend on?”

Noted civil rights attorney Benjamin Crump, who is representing the Arbery family, predicted the defense would ask the judge for a mistrial because of the demonstration outside the courthouse.

“We need preachers to come pray for them in this insane situation, this inhumane situation,” Mr. Crump said. Earlier, people in the crowd chanted the names of Black people who have been killed in high-profile cases in which racism or police brutality were alleged.

Church vans from a wide range of denominations were parked along streets around the courthouse. The Rev. Gregory Edwards was broadcasting a Facebook Live video back to his friends in Allentown, Penn., where he is pastor of the Resurrected Life Community Church, United Church of Christ.

As soon as the call for pastors to come to Brunswick went out, Rev. Edwards said, he rearranged his schedule to fly down.

“I would have walked,” said Rev. Edwards, who also runs a multi-faith, multiracial community organizing group. Rev. Edwards said he cried when he saw the video of Mr. Arbery’s shooting death and thought of his three Black adult sons.

“Through technology we have been forced to bear witness to the public executions of our Black brothers and sisters,” Rev. Edwards said.

A group of businesses in Brunswick and surrounding Glynn County joined together to provide a lunch of free barbecue sandwiches, shrimp and side dishes before the pastors rallied. Organizer Mike Mally said the group wanted to show that the community was united, not divided by race.

“We figured this was a good thing to do with all these visitors,” Mr. Mally said.

Cellphone video of Mr. Arbery’s death on Feb. 23, 2020, leaked online about two months later, deepening a national outcry over racial injustice. None of the three white men charged in the killing of Mr. Arbery had cause to make a citizen’s arrest when they saw him in their neighborhood, according to a prosecutor, who said Monday in closing arguments that the defendants decided to pursue him “because he was a Black man running down their street.”

Closing arguments before a disproportionately white jury were held Monday after 10 days of testimony that concluded last week. The man who shot Mr. Arbery claimed during his testimony that he pulled the trigger in self-defense.

Father and son Greg and Travis McMichael grabbed guns and pursued Mr. Arbery, 25, in a pickup truck after spotting him running in their neighborhood. A neighbor, William “Roddie” Bryan, joined the chase and recorded the video of Travis McMichael opening fire as Mr. Arbery threw punches and grabbed for the shotgun.

No one was charged in the killing until Mr. Bryan’s video leaked and the Georgia Bureau of Investigation took over the case from local police. All three men face counts of murder and other charges.