A street preacher involved in a stabbing at a Canberra shop last year has told the ACT Supreme Court he could have killed the victim if he had wanted to.

Isa Islam, 37, is on trial for attempted murder, intentionally inflicting grievous bodily harm and using an offensive weapon.

The former RAAF employee told the court he had been preaching about the Islamic faith outside the Ainslie shops that morning.

Later that day, he saw his former neighbour in a nearby take away shop.

Islam told the court he believed the man knew who had been breaking into his Ainslie Village room and vandalising his belongings.

He said after his neighbour refused to talk to him he just snapped and started stabbing him.

But he said he certainly did not mean to kill him, saying if he had wanted to he could have cut his throat.

A verdict is expected next year.