Sunrise host Nat Barr asks the question on the minds of many Australians after horrific church stabbing attack in Sydney

Natalie Barr has asked the question on the minds of many Australian after a 16-year-old boy allegedly attacked a high-profile bishop during a live-streamed sermon in Sydney's west.

In a video of the attack, the boy in all black is seen approaching and stabbing Bishop Mar Mari Emmanuel in the head and chest at the altar of the Christ The Good Shepherd Church in Wakeley at about 7.10pm on Monday.

Horrified parishioners are seen rushing to the bishop's aid while others grabbed the assailant and held him captive inside the church.

The terrorist attack has sent shockwaves around Australia following the deaths of six innocent shoppers at Westfield Bondi Junction on Saturday.

Barr asked former NSW deputy police commissioner Mick Willing how the alleged attacker may have become radicalised.

She asked: 'Where does someone like this come from? Are they sort of sitting on their computer, in their spare bedroom, being turned into a terrorist?'

Mr Willing said it was a 'difficult question' to answer due to the limited information currently known about the alleged attacker's background. 

'In answer to your question Nat, sometimes that does occur,' he said.

'Sometimes people get radicalised online, sometimes their radicalised in different ways. So every situation like this is unique unfortunately.

'All of that will be part of the investigation, they will search holdings across a range of agencies to see whether or not he was known to authorities.'

The 16-year-old boy was captured on the live stream of the attack shouting 'Allahu Akbar' as he stabbed the bishop in the head, neck and torso at least eight times. 

Horrified parishioners leapt into action, with some rushing to the bishop's aid and others helping to detain the teenager inside the church.

Video showed the alleged 16-year-old perpetrator detained by police on the ground inside the church before he spoke in Arabic.

It is understood the words translate to: 'If he didn't swear at my Prophet I wouldn't be here. If he didn't involve himself in my religion I wouldn't be here'.

One of the men involved in restraining the teenager following the attack, before police arrived, described how he approached the teenager from behind and forcefully pushed him to the ground.

'He kept saying: "Allahu Akbar, Allahu Akbar",' the man said in a video posted to social media.

The Australian National Imams Council and the Australian Muslim community have unequivocally condemned the attack on Bishop Emmanuel.

'These attacks are horrifying and have no place in Australia, particularly at places of worship and toward religious leaders,' they said in a statement.

Shock new details emerge about criminal record of teenage boy 

The teenager was charged with a number of offences after an incident at a Sydney train station in November last year, reported the ABC.

The charges included possessing a flick-knife, being armed with a weapon with intent to commit an indictable offence, stalking and/or intimidation and recklessly destroy or damage property.

He had been on bail before a court appearance in January where the charges were 'proven' but dismissed with the good behaviour bond.

The outlet reported there were no supervision orders in place when he allegedly carried out the attack on Monday night.

'Miracle' saves life of bishop 

Bishop Mar Mari Emmanuel's life was saved when his alleged attacker's flick-knife failed to open properly. 

Close friend Danny Abdallah spoke to the bishop as he recovered in hospital overnight and revealed fresh new details of the incident on Tuesday morning.

Mr Abdallah - who lost three of his children and his niece to a drunk and drugged driver - called the bishop's miracle escape an 'act of God'.

The bishop remains in hospital after undergoing surgery on Tuesday.

Meanwhile, temporary powers have been granted to police to allow them to search people, vehicles and property following the alleged attack. 

The incident was declared an act of terror by NSW Police Comissioner Karen Webb and confirmed by the Police Minister which triggers the legislation in the state. 

Officers will be able to search people, vehicles and properties without a warrant, establish roadblocks, cordon off areas and demand confirmation of ID's. 

The powers, granted to prevent any further attacks, will last for two weeks.