It's difficult to comprehend the depths of horror that occurred in the vast Westfield shopping centre near the famous Bondi Beach in Sydney last weekend. A 40-year-old man, dressed in an Australian Rugby League shirt would have appeared innocuous – just a normal part of the crowd. Instead, he ended up killing six people with a knife, and injuring seriously eleven others, including a baby.

The dead included the mother of the baby, an architect, a refugee who worked as a security guard, an artist originally from the country of Georgia, and a bride to be out shopping for her wedding. Five of the six killed were women, as were eight of the survivors.

The murders, and the reactions to them reveal a great deal about our society – the good, the bad and the ugly.

What good can there possibly be in such senseless violence? A great deal. Take for example the mother who died as she sought to protect her baby. Dr Ashlee Good took her baby out of the pram and handed her to a couple of strangers, before she was then attacked and killed.

Or the policewoman, Inspector Amy Scott, who confronted the man and then when he turned on her, shot him dead. Probably saving many more lives. Or the two men who ran towards the danger and sought to prevent the murderer advancing up an escalator. The delay they caused also saved lives.

And then there was the security guard who was killed. Faraz Ahmad Tahir was a member of the Ahmadiyya Muslim community who had come to Australia as a refugee from Pakistan – where the Ahmadiyyas are persecuted by more orthodox Muslims.

The courage and compassion of many involved revealed the best of human nature. But of course we also saw the worst - especially in the reactions.

Sadly, in our instantaneous world, people are far too quick to jump to conclusions – without knowing what has actually happened. As news came out of Sydney, the internet was awash with people, including some well-known commentators, declaring that this was yet another example of an Islamist attack. It wasn't.

But perhaps even more horrifically within hours it was being widely reported that a young Jewish student was the person responsible. When I woke up on Sunday morning his name was all over the internet – and those who seem to spend every waking hour commenting on Palestine were quick to gloat about 'Jewish terrorism'. One mainstream TV station in Australia added fuel to the fire by naming him as the suspect. His name was mentioned over 50,000 times in social media.

Islamism? Jewish terrorism? The only one missing was the usual 'Far Right' cry. The truth is that even if the murderer had been a Muslim, or a Jew, or even expressed Far Right opinions, it may have had little to do with the killings – which seem to have been the result of a severe mental health illness. But such is the tribalisation of our society that people look to find 'evidence' for their prejudices – even in the midst of such tragedy.

We need to be careful when speaking about mental health as well. Most people who are mentally ill are not mass murderers. We must not demonise those who suffer from poor mental health. Neither must we allow mental health to be used as an excuse for evil. It is possible that someone could lose all sense of moral compass that they are no longer responsible for what they do – but that is an extreme. It happens. But it is rare.

The real murderer, Joel Cauchi, from Queensland was known to the police for having serious mental health issues related to schizophrenia – although he had no criminal record. He came to Sydney a month ago and had been living in a vehicle. He appears to have had an obsession with knives, but other than that his Facebook posts exude normality showing an interest in surfing, visiting the Sydney Opera House and eating curry. However, he did advertise himself as a male escort offering graphic sexual services.

It is clear he was a severely disturbed individual – and that in itself raises questions about how we help those who suffer from severe mental illness, especially when they may end up causing such devastation. I suspect a society which encourages violence and prostitution is not a healthy one for an unhealthy individual to be in.

The fact is that this situation could have been a lot worse. I've seen some argue that if Australians carried guns these killings would not have happened. That is to say the least, simplistic and unwise. The corollary is that if Cauchi had had guns we could have been looking at a Port Arthur style massacre. In 1996 a gunman killed 35 people in Port Arthur in Tasmania. After that Australia's gun laws were massively tightened with heavy restrictions on the use of automatic and semi-automatic weapons. I have no doubt that this legislation has saved numerous lives – including this past weekend in Sydney.

Meanwhile as I write news has come of a the stabbing of Bishop Mar Mari Emmanuel and three others in the Assyrian Orthodox Church in Wakeley, West Sydney. Bishop Emmanuel is a well known and sometimes controversial Christian commentator and his stabbing during his live streamed service was astonishing. This time the NSW government have declared it a terrorist incident, because the teenage attacker appears to have been motivated by his Islamic faith.

According to news sources he is alleged to have said that his motivation for the attack was that he believed the bishop had attacked his prophet Muhammad. The attack resulted in riots outside the church – with 20 police vehicles being damaged and several people, including police officers, being taken to hospital.

In all of this we are reminded that we all live in a broken world where there are broken minds, broken bodies, broken homes, broken hearts and broken societies. We can only pray for, and long for, healing. A healing which ultimately comes only through Christ. We weep with those who weep, and we cry 'How long, O Lord, how long?'

David Robertson is the minister of Scots Kirk Presbyterian Church in Newcastle, New South Wales. He blogs at The Wee Flea.