Influential extremist preacher Robert Cerantonio, who led a failed plot to sail to the Philippines in a "boat that could have sunk in a bath tub", doesn't fit the profile of an Islamic extremist partly because of his "eclectic taste" in music, his lawyer has told a Melbourne court.

Key points: Philippines plot ringleader Robert Cerantonio converted to Islam as a teen after becoming disillusioned with Catholicism

Philippines plot ringleader Robert Cerantonio converted to Islam as a teen after becoming disillusioned with Catholicism He had music by ACDC, Bob Marley, Edith Piaf, Cold Chisel and Queen on his phone when he was arrested

He had music by ACDC, Bob Marley, Edith Piaf, Cold Chisel and Queen on his phone when he was arrested Cerantonio's co-offenders in the failed scheme to overthrow the Philippines government have already been sentenced to jail terms

Cerantonio, 34, was the leader of a group of five men arrested after towing a boat from Melbourne to Cape York in Far North Queensland in 2015.

They planned to sail to the southern Philippines and work with Muslim militants to overthrow the government there.

The Footscray man faces a maximum penalty of life imprisonment after pleading guilty to entering an agreement to do preparatory acts to overthrow a government by force or violence.

Cerantonio's plea hearing in the Victorian Supreme Court was told he had published an article a year before his arrest in which he wrote: "We as Muslims must fight the Philippine government as they are the ones who have taken control of our lands from us."

Cold Chisel, Edith Piaf on his phone

Despite the extensive catalogue of extremist lectures and articles Cerantonio had published online, defence barrister Jarrod Williams told the hearing he did not fit the stereotypical profile of an Islamic extremist.

"He has some quite literal interpretations of certain religious texts and yes, it is true, over the years he has powerfully advocated and prosecuted those views in public fora," he said.

"But … it's not as simple as saying: 'Well this man supports IS, he supports everything they say and he's a fanatic'.

"His views are somewhat nuanced."

Mr Williams said this was evidenced by the fact Cerantonio had an "eclectic" mix of music on his phone when he was arrested which included artists such as ACDC, Bob Marley, Edith Piaf, Cold Chisel and Queen.

The court heard the influential preacher had lived in the Philippines for a year from June 2013 and used his time there to encourage others to use violence in an effort to establish an Islamic state governed by sharia law.

He was arrested in the Philippines in 2014 while in possession of documents and images relating to the Islamic State terrorist group and violent jihad.

Cerantonio's passport was cancelled after he was deported to Australia.

Neither Cerantonio or his five co-offenders, Paul Dacre, Antonino Granata, Kadir Kaya, Murat Kaya and Shayden Thorne, had passports allowing them to leave Australia when they hatched the plan to travel covertly to the southern Philippines by boat.

Justice Michael Croucher said their journey was doomed to fail as the men had "less idea than the passengers of the SS Minnow", referencing the fictional charter boat in the 1960s television sitcom Gilligan's Island.

"[The] boat … would have sunk in a bath tub I reckon," he told the court.

Robert Cerantonio avoided questions from the media after arriving at Melbourne Airport in 2014. ( ABC News )

Extremist preacher converted to Islam

Cerantonio was raised in a Catholic family in Melbourne's western suburbs and was a talented student and footballer as a teenager, the court heard.

But he converted to Islam at the age of 17 when he became disillusioned with Catholicism after visiting the Vatican and seeing depictions of God he believed were contrary to mythical teachings.

Justice Croucher said he had been surprised by Cerantonio's typical upbringing.

"You talk about a perfectly ordinary Australian kid growing up who's bright, capable, likes his sport … but then he ends up holding these views and doing what he did," he said.

"Where did it all go wrong?"

Cerantonio's defence barrister Jarrod Williams said despite his client having advocated for the Islamic State terrorist group, there was no evidence he supported terrorist acts being committed in Australia.

"His preference in life would be to live in a Muslim country and indeed to live under sharia law," he said.

Prosecutor Richard Maidment QC said there was no evidence Cerantonio had renounced his views and although he hadn't advocated for terrorism within Australia, he had encouraged terrorist activity in the Philippines.

Cerantonio faces a maximum penalty of life imprisonment after pleading guilty to entering an agreement to do preparatory acts to overthrow a government by force or violence.

He will be sentenced on April 29.

Cerantonio's co-offenders have already been jailed for their roles in the plot.

Last month, Paul Dacre, Antonino Granata and Kadir Kaya were each sentenced to four years in prison, with a non-parole period of three years.

Murat Kaya was sentenced to a jail sentence of three years and eight months, with a non-parole period of two years and nine months.

Shayden Thorne was sentenced to three years and 10 months in prison.