CST volunteer Jonny Dryer ushered members inside the shul after he saw the man running directly towards him down the narrow alley leading to the building.
Mr Dryer then protected a woman and two children left outside, acting as a human shield between them and the knifeman, police said.
Awarding Mr Dryer the commendation, Barnet borough commander Detective Chief Superintendent Simon Rose praised him for his heroism with “no regard for his own safety”.
Mr Dryer received the award from Det Ch Supt Rose and the Mayor of Barnet, Councillor Brian Salinger, at a ceremony on Thursday January 11.
Det Ch Supt Rose told the JC: “It was a pleasure to recognise Jonny’s bravery in stepping forward into the face of danger.
“Although this eventually turned out to be a false alarm with the suspect suffering a mental health episode, to everyone at the time, it looked and felt like the real thing.”
