Zundel faces deportation to Germany after Ottawa classified him as a threat to national security last week.
"I'm a pacifist," he said from the witness stand while testifying in his own defence inside a packed Toronto courtroom.
Federal Court documents, based on evidence provided by the Canadian Security Intelligence Service, say Zundel is a flight risk who must be held in detention until he can be deported.
The security certificate process provides for virtually unlimited detention until a person has been deported or a judge strikes it down.
At times, Zundel even shed tears as he denied advocating or condoning violence and insisted he has no ties with racist groups.
He told the court he believes he owes Hitler his life because his parents were too poor to raise a family until Hitler came to power and brought Germany "peace, honour and a place in the sun."
Hitler, Zundel argued, is as misunderstood as he is.
For many Jewish groups represented in the courtroom, it came as a disturbing spectacle.
"The fact he is evoking Hitler's name and trying to justify some good to Hitler, the madman, is incredulous," Frank Dimant, executive vice-president of B'nai Brith Canada, said after the hearing.
Zundel, 64, lived in Canada for 42 years before departing the country three years ago for the United States.
The hearing is scheduled to continue to May 16, when the judge will have to decide whether Zundel and his ideas are a reasonable threat to national security and warrant deportation.
