Bali bomber Idris says it will be for Allah to decide if what he did was right or wrong in helping carry out the attack which killed 202 innocent people.

For someone who carved such a jagged scar across Australia's recent history, the man sitting across from me is disappointingly ordinary.

He cracks a joke and chuckles. It's clear he wants to be liked. He describes himself, accurately it seems, as ''not extra intelligent and also not extra stupid''.

The man is Idris: a Bali bomber, a senior member of the terrorist organisation that planned and then carried out the attack 10 years ago that killed 202 people including 88 Australians.

What he and his cabal did change everything. It ended Australia's isolation from violent global jihad, pulling this country emphatically into world events. It shocked Indonesia into a sustained crackdown on the radicals multiplying in its midst. And it ripped bodies apart, burnt flesh and marked thousands of survivors and families forever, both physically and psychically.

But ask him for an explanation of what he did, for some deep reflection, and Idris comes up with the lamest of all possible answers: he was just following orders.

In his first ever interview with Australian media, the freed bomber says he would willingly wage jihad on Indonesian soil again, but only if he believed he was fighting in a ''legitimate war zone'' - which includes armed inter-religious conflict on Indonesian soil.

''If some time in the future I form the intention to do jihad, it is obvious that I'll go to war. If there is such a zone in Indonesia, of course I will go there.''

But the most senior Bali terrorist to be released from jail has also told The Sun-Herald he remains unsure whether his role in the bombing was justified under Islamic law.

''I have never felt glad, happy or gay about this affair. In my heart I keep hoping that what I did was right and that I will be rewarded,'' he says. ''However, I'm always worried that it was wrong and that Allah will punish me.''

Idris was 12 kilometres away on a motorcycle with his fellow terrorist Ali Imron when he felt as much as heard the Bali bomb go off.

''It's as if it came from underground,'' he recalls.

As the subterranean rumble reached him, he did not spare a thought for the victims. His thoughts were only for himself. ''The feeling of fear dominated,'' he said in his home town of Pekanbaru.

''[Ali Imron and I] went to a restaurant. There was rice in front of us. We couldn't finish it, not even a quarter of it. Even water tasted bitter … No one talked. We heard the sirens, ambulance, we felt really afraid.''

Idris can only speak now because he is a free man. He escaped conviction for the Bali bombing on a legal point when Indonesia's constitutional court ruled he could not be convicted under laws passed after the bombing took place.

He was sentenced to 10 years in jail for a different bombing, of the Marriott Hotel in Jakarta in 2003, which killed 12 people. But after remissions and parole served just five years. He was released in 2009.

He lives with his family but complains he cannot find work because his past means no one will give him a job.

Idris attended Ngruki, Abu Bakar Bashir's school of jihad in Solo, but his book learning did not lead to action until 2002. Then, two of Indonesia's most important jihadis, Amrozi and Mukhlas, the supreme leader of Jemaah Islamiah in Asia, called him to a a little house in Solo. It was a planning meeting for a bomb attack on ''America and its allies'' in Bali - a place they saw as a nest of infidel hedonism.

Idris became project manager. ''My role … was to provide logistics and to prepare various things, such as providing a house, car, surveying the target, and also preparing food. Basically anything my friends might need.''

Idris also remembers Mukhlas, who was executed in 2008, was the one giving the orders. To Idris, everything he did can be explained by that single fact. ''I couldn't think about if [the attack] was justified or not justified. If the senior commander ordered us to do it, we had to.''

What about conscience? Humanity? ''I didn't think, I simply followed what Mukhlas said.''

Idris also refuses to feel bad about being released from jail.

''It is the state who created the law … Whether it was fair or not I cannot say,'' he says.

But the questions of personal responsibility and remorse continue to rankle. I show Idris pictures from The Sydney Morning Herald taken in 2002 of maimed and burnt bodies, of the wreck of buildings and the remains of the van that contained the bomb. I ask him how he feels and he pauses for thought.

''When I saw the pieces of bodies I just thought something like, 'Wow', or 'Oh, my god', because I know there isn't any Islamic law about this,'' he says.

''It's like: 'Look how much damage I did.''