An unhinged 22-year-old man has been arrested for making threats to Big Apple synagogues, sources said.

The suspect, Christopher Brown, was collared at the Long Island Rail Road platform at Penn Station late Friday night, carrying weapons and a Nazi armband recovered in his bag, the sources added.

The twisted suspect was wearing a T-shirt that said, “I have a gun and I’m schizophrenic,” according to the sources. The phrase on the shirt was written in reverse.

The FBI/NYPD Joint Task force had been on the trail of Brown, a “diagnosed schizophrenic” who recently made overtures to family that he was interested in going to New York and buying a gun, the sources said.

Brown, of Aquebogue, was arrested at 11:30 p.m. and charged with making terroristic threats, aggravated harassment and criminal possession of a weapon, the NYPD said.  

When Brown was arrested he had the arm band, a ski mask and a large hunting knife, sources said.

The threats — which escalated on Friday — were allegedly made on Twitter, sources said. Cops also recovered a Glock 17 with an extended magazine, the sources said. The weapon was found in a backpack in the Upper West Side home of 22-year-old Matthew Mahrer, the sources added. He was charged with criminal possession of a weapon, the sources said. Brown and Mahrer are believed to have been traveling together, the sources added.

NYPD Commissioner Keechant Sewell praised the “sharp-eyed” law enforcement action in the case.

“The FBI/NYPD Joint Terrorism Task Force, NYPD Counterterrorism and Intelligence Bureau investigators, working with their law enforcement partners, uncovered a developing threat to the Jewish community on Friday and moved swiftly to gather information, identify those behind it, and operationally neutralize their ability to do harm,” Sewell said in a statement.

“As a joint investigation now continues to establish a strong prosecution, Police Department commanders are strategically deploying assets at sensitive locations throughout New York City.”