"That' really my take on it.
"I think their ideology is abhorrent, their actions are abhorrent and the destruction of monuments is again evidence of this abhorrence.
"Destruction of monuments is just another thing in a grand list of despicable abhorrent acts. They don't have respect for these things, no respect for history."
Dr Ali said he did not limit this word to Islamic State's actions towards ancient sites and monuments.
"Even more important is how they are treating people. If they are prepared to destroy monuments - they're ancient, they're old, they're made of rock ... just imagine what it is like for people.
"Unlike statues, people feel pain."
Dr Ali said Isis continued to become more brutal and vicious towards people for several reasons.
He said the "shock value" of their actions got them into the news, and gave them publicity.
"It serves military purpose as well. They're in a war and these type of activities send out a message that if you're there to oppose us, this is what you will face.
"It is a tool of intimidation.
"They're under a lot of pressure at the moment, according to a lot of news reports, Isis is losing territory. This is a way to deflect the attention away from their losses, and by being in the media with these sort of activities it's sort of a show of strength.
Associate Professor of religion at the University of Otago Greg Dawes said one would expect a group such as Isis to be destroying monuments that were representing Pagan religion.
"But what Isis seem to be doing is much broader than that. They certainly do seem to be destroying sites that represent Pagan religion, and also they seem to be targeting some of the Shi'ite sites as well, because of course they're a radically Sunni group.
"I wonder too, whether some of it is simply a matter of gaining attention, like the YouTube videos beheading captives and so on, which I think are as much a matter of publicity as they are principal.
"I think they've probably got a religious motivation and a broadly political one."
Dr Dawes said an interesting feature of revivalist groups such as Islamic State was that they had the view that the original Islam, was the pure Islam.
"Shortly after that Islam went into a decline and became contaminated with Pagan beliefs, and so the Islam they see around them they tend to regard as degenerate.
"They have a very strange view of history in the way that the history worth preserving is the original one, but much of what followed was a corruption of the original Islam.
"They tend to not have a lot of respect for much of what we might think of as their own history."
