A Humboldt Park man was found guilty Friday of aggravated battery charges for stabbing a man who confronted him about his purported membership in a white nationalist group outside a concert at Northerly Island in 2017.

Brushing aside claims of self-defense during a two-day bench trial, Judge William Hooks found that Thomas Christensen badly overreacted to a “sophomoric” confrontation with a 30-year-old fellow concertgoer who called him out as a member of the white nationalist Proud Boys and got in a scuffle that left Christensen with cuts on his lip and scalp.

“The reaction of the defendant to his interactions and his confrontation, where he was confronted by this rather immature, sophomoric victim, was disproportionate. It was over the top,” Hooks said.

Donning a pair of rubber gloves and removing the knife from a box on his desk, Hooks examined the “folding dagger,” pulling out a tape measure to mark the length of the blade at about 3 inches.

“These were death blows,” Hooks said. “The defendant has already won, because this is not a murder case.”

Hooks revoked bail for Christensen, who had been free on $250,000 bond since his arrest in 2017. Stripping off his watch and handing his wallet to his attorney, Christensen walked out of the courtroom to a holding cell, escorted by courtroom security officers.

Outside the courthouse, Christensen’s friend, Nick Stiso, said Christensen was indeed a member of the Proud Boys, a group Stiso described as a “fraternity” that is “pro-American.” He said the group is often misidentified as a white nationalist or white power group.

The verdict against Christensen was not surprising, Stiso said.

“Chicago has been very corrupt for a long time against anything that’s pro-conservative,” said Stiso, who said he lived in Englewood before moving to the near west suburbs. “The Democrats have had a stranglehold on this city for six decades, and they act like thugs.”

Christensen was one of several people wearing Proud Boys garb at an April rally, organized by the Chicago Fraternal Order of Police, protesting African American Cook County State’s Attorney Kim Foxx.

At trial, Christensen said he works in real estate and had previously been a preschool teacher.

Stiso said Friday his friend was a nice guy.

“He’s actually very laid-back,” Stiso said. “He was attacked. He may have overreacted, but that’s why he acted the way he did.”