"There's no doubt in my mind people are going to come out of this movie disliking Muslims and Arabs more than they already dislike them," says the professor of Islamic law at the University of California.
"In my view, it is inevitable – I'm willing to risk my reputation on this – that after this movie is released there will be hate crimes committed directly because of it. People will go see it on a weekend and decide to teach some turbanhead a lesson."
Scott has said he intended to make a film about a noble knight and settled on Balian of Ibelin, portrayed by Orlando Bloom. In 1187, Balian defended Jerusalem against the Muslim leader, Saladin, played by Ghassan Massoud, and lost. However, the religious context of Balian's story dominated discussion of the production and, as soon as the script for the £75m production became available, the New York Times passed copies to five experts on the Crusades, one of them Abou El Fadl.
One expert has defended the script, saying it contains nothing that should upset Christians or Muslims, but criticisms from others range from historical inaccuracies to character and cultural misrepresentations and claims of insensitivity to current perceptions of Islam in the western world.
The criticisms were echoed when British experts attended a Kingdom of Heaven junket, during which Scott talked about the plot and its purported historical accuracy. Questions from the audience were not permitted, but Dr Jonathan Phillips, a member of the audience and a lecturer in history at Royal Holloway, University of London, knows what he would have asked.
"The main problem is he's got this idea that the noble knight and Saladin could have made peace, but a few people wrecked that for secular motives such as greed," says Phillips, author of The Fourth Crusade and the Sack of Constantinople. "He's got a religious subject and I think he's secularised it in part. He wanted to make a film about a knight as an icon. He's done that, but in a context where religion is saturating the concept of a knight in a Crusader context.
"The question is whether it's an appropriate subject right now and whether he has done it in a way that is appropriate."
While academics acknowledge that a degree of artistic licence is to be expected with any big-budget Hollywood movie, many agree that the religious context of the Crusades warrants a careful depiction, given the current religious and political climate.
Phillips believes that although Scott initially defended the accuracy of the film, he has begun to climb down as more and more criticisms emerge.
Some of these are of little consequence; for example, Balian is portrayed as a blacksmith who becomes a knight. He was, in fact, according to Phillips, "born to the top table". The leper king, Baldwin, makes an appearance, in spite of having died two years earlier. However, others are seen to propagate stereotypes of Muslims that could have dangerous consequences, as Abou El Fadl predicts.
"There's a single (Muslim) character who is human-like – Saladin, he has consciousness and awareness," he says. "There's another character who is a mad, ranting, raving, blood-thirsty lunatic, screaming 'jihad, jihad, jihad'. The rest of the Muslim characters are willing to die without any emotion."
Abou El Fadl says he anticipated this pattern of characterisation; that in any western film involving Muslims he has come to expect only one complex character surrounded by many simplistic others. He also predicted that Saladin would be portrayed as being conflicted about his Islamic identity, though not to the extent that the script suggested.
"This movie actually went a step further, which I found deeply, deeply offensive," says Abou El Fadl. "Despite the savagery of the Crusaders and despite their ability to commit massacres and pillage and rape [of which he acknowledges the Muslims were also capable], Saladin identifies with them and is nearly sympathetic towards them. In one of the most unbelievable scenes, though I don't know if it stayed in the movie, Saladin thanks the Crusaders for teaching Muslims chivalry."
Phillips agrees that the Muslim characters, bar Saladin, are under-developed. "From what I saw, they're not described at all. They 'howl and gabble', which are the twelfth-century terms used to describe them, and they're not really treated as individuals."
Some experts have identified problems with how Saladin – the one Muslim character the audience can empathise with as a human – conforms to the stereotype promoted by Scott in The Talisman, Saddam Hussein and former Syrian dictator Hafez Assad. Scott is acknowledged to have romanticised the Muslim leader, while Hussein and Assad commissioned statues of him to consolidate Arab Muslim identity (though he was a Kurd).
Phillips believes this "soft-focus" portrayal diverts attention from Saladin's motivation. "There's a layer in this movie that doesn't take on board that, although Saladin was an honourable man, his career was based on throwing the Christians out," he says. "His rise to power revolves around jihad, the holy war, so, while he can be treated as an individual, Christians were the enemies of his faith. He's rather more hard underneath than Scott's."
Abou El Fadl believes that, beyond individual characters, Muslim culture is overlooked and notes that, while the film includes sequences of Muslims jumping on crucifixes, little is communicated about the comparative sophistication of Islamic society at the time.
"The historical record is established in that the Europeans find a superior culture invading it and learn to indulge in the luxuries the Muslims had become very good at enjoying," he says. "You don't even get a hint that there's an Islamic law that regulates warfare; that the slaughter of innocents is strictly prohibited in the Koran."
Abou El Fadl believes an opportunity to encourage understanding between Christians and Muslims has been missed, though he won't commit to saying whether he believes it is intentional. "I'm not a conspiracy-theory type, but the timing of this movie is most suspect," he says. "The film falls in the category of 'it's okay to invade these people, something good will come out of it'. Not only that, but the fanatics are better off dead because they want to go to heaven.
"This at a critical time when the logic of the white-man's burden is coming back through the invasion of Afghanistan and Iraq and a lot of people are wondering if there is a civilisational showdown between Islamic and Christian culture."
Kingdom of Heaven opens on May 6.
In The Herald tomorrow: part two of The Real Crusades. Beth Pearson goes in search of the truth.