Melbourne murder accused James "Dimitrious" Gargasoulas wants to go to trial over the Bourke Street rampage so he can tell people he is the Messiah and prompt an uprising against the government.
Forensicare consultant psychiatrist Andrew Carroll on Thursday said the 28-year-old had expressed a desire to stand trial over the 2017 Bourke Street mall rampage.
"He absolutely wanted to make sure he had a trial of some kind so that he has a platform (for his Messianic beliefs) so the public can ask questions," Dr Carroll told the Victorian Supreme Court.
"In his mind that would lead to an uprising."
Gargasoulas is facing an investigation hearing before a jury to determine if he is fit to be tried on six counts of murder and 28 charges of attempted murder over the mall incident.
Dr Carroll is the third psychiatrist to tell the hearing that Gargasoulas suffers from schizophrenia and is unfit for trial.
Prosecutor Andrew Tinney SC said Gargasoulas' ability to discuss his court case implied he was capable of making a decision about whether to plead guilty or not guilty.
But Dr Carroll said Gargasoulas' reasoning was heavily influenced and compromised by his delusional beliefs about being the Messiah.
"His delusional beliefs are of such a nature that he is unable to rationalise the options that are open to him," the psychiatrist said.
"In my view this renders him unfit to stand trial."
Dr Carroll said Gargasoulas may be able to verbally enter a plea, but that does not mean the 28-year-old had made a rational decision free of delusions.
"It can't just mean can he speak the words," Justice Lex Lasry said.
"Exactly, Your Honour," Dr Carroll replied.
The hearing continues.