Kingdom of Heaven is a far, far more interesting film than most of its reviews have suggested and a far, far more morally complex film than any of Ridley Scott's recent offerings. Like Gladiator, it focuses on one individual to illuminate a period. Unlike Gladiator, the road travelled is not from injustice to revenge but from sin to fulfilment. Kingdom of Heaven is set in 1184, after the first crusade during an interlude of uneasy peace between Muslim and Christian in Palestine.

There is much in Scott's portrayal of events that is broadly accurate though he is no exception to the rule that films, like Shakespeare's plays, usually do to history what they do to novels - sacrifice faithfulness to the original, either to fit the demands of the cinematic medium, or to make points about the present. That said, neither Scott nor the studio can be condemned for cowardice. After 9/11, two wars against Iraq and a very clearly unresolved Arab-Israeli conflict, Scott goes where angels might indeed fear to tread.

Certainly, as far as the potential for peace between Christian and Muslim nations he is optimistic, but not by avoiding some of the realities of the crusading mentality. On the one hand he rightly understands that the primary motives of those who "took the cross" were spiritual rather than material or territorial. On the other hand, he does not flinch from putting the familiar words "To kill an infidel is not murder. It is the path to heaven" in the mouth of a monk. The core of the film, however, lies in the spiritual and moral journey of its central figure, Balian, played by a swarthy, post-Legolas, bow-free but martially adept, Orlando Bloom.

For Balian, the kingdom established by the first must be: "A kingdom of conscience or nothing at all". Indeed, the central driving force of the drama is the exploration of the interplay of loyalties and principles - to king, to duty, to faith, to love, to conscience. Of course, Scott cannot resist a good fight, giving us a range of combat situations - one to one, cavalry charges, set piece battles and sieges. All are shot with a visceral intensity that certainly justified its 15 rating. However, the violence primarily serves to illuminate the consequences of choices. In this, the film, like Scott's Black Hawk Down, avoids a crude cowboys and Indians conflict between Muslim and Christian. The real enemies of peace are not defined by their faith, but by their distortion of it.

The plot is simple enough. Balian, a French blacksmith, discovers that he is the bastard son of a nobleman who offers him his birthright if he comes to his estate outside Jerusalem. At first, Balian refuses, mourning the loss of his wife who committed suicide after the death of their young son. But when, in a fit of rage, he murders the priest who stole the crucifix from her corpse, he takes to the Jerusalem road.

Balian's quest, however, is not for fame or fortune but for forgiveness for his sins and for those of his wife. As the story progresses Balian takes the vow of a knight and finds himself at the centre of a struggle between rival factions of Christians. King Baldwin, a leper since the age of 12 and still young, seeks to find a way to keep Jerusalem safe for Jews, Christians and Muslims by restraining the war-thirsty Templar Knights from inciting the formidably powerful Saladin. This, in the film, is the true kingdom of heaven - a period of mutual respect and generally peaceful co-existence.

Balian meanwhile pursues the principle that was carved into the cross beam of his humble smithy:

'What man is a man who does not make the world better.'

So he digs wells to irrigate the land he inherited from his fatherand help his people flourish. The idyll is broken when Reynald de Chatillon, accurately portrayed as an impulsive, rebellious Christian nobleman (cf the excellent The Crusades, An Illustrated History, W B Bartlett, Sutton, 1999) attacks a Muslim caravan. Saladin's army mobilises to retaliate and Balian is presented with the first test of his knightly vow: safeguard the helpless. As Saladin's army closes in and threatens to slaughter the peasants fleeing into the city, Balian and his small squadron of knights chooses to attack Saladin's overwhelmingly superior force to give the peasants time to reach safety. Most of his knights are killed but he is spared and the peasants survive.

Oaths are to be kept, even if it hurts:

"Lord, who may dwell in your sanctuary?
... (he) who keeps his oath
even when it hurts …" (Psalm 15: 1 & 4)

Such sacrificial actions arise from a strong sense of duty and from the understanding that power is not primarily to be exercised for the benefit of the leader but for the benefit of the people: "Defend the King", Balian's father had urged, "And if the king is no more, protect the people." This servant perspective on power finds frequent expression. So, for example, the ailing King Baldwin leads his army out to face Saladin in the field and sagely negotiates a peace, knowing that the exertions of the journey will hasten his death. And they do.

Death in this film is not the enemy but moral compromise is. Indeed, later in the film, when Balian tells a crusader friend that the new king's sortie will lead to certain death, he replies: "All death is certain." And carries on. His vows of allegiance override concern for personal safety.

The most striking example of principle before self-interest comes when the heirless King Baldwin offers Balian his sister Sibylla in marriage so that Balian can rule as king and pursue Baldwin's conciliatory policies. Balian refuses because it will involve the assassination of Sibylla's husband - his enemy and a man entirely unfit to rule who will foment conflict and bring destruction on the Kingdom. Disappointed, Sibylla rebukes Balian:

"There will be a day when you had wished you had done a little evil to do a greater good."

King David's men might well have said something similar when he twice spared Saul.

Sibylla's is the world of realpolitik and, in the context, Balian's decision does at first seem legalistically squeamish. Would it not be better as Caiaphas put it: "that one man die for the people than that the whole nation perish." (Cf John 11:50) How easy to make a Caiaphasian compact. Balian, however, will have none of it.

In the end it is not entirely clear whether Balian finds true faith, but it is clear that he finds peace and that true goodness lies in the head and in the heart and finds expression in service and faithfulness, in seeking peace and not the destruction of those made in the image of God who have a different faith. Amen to that.

Saladin too is presented as a man of high integrity, respect for the 'infidel' and compassion, consistent with the most contemporary accounts, In the final scene, Jerusalem now in his control, he walks through the King's palace and finds an altar crucifix on the floor. He picks it up and puts it back on the altar. It is clearly intended as a model for contemporary Muslims. A rather optimistic one.

Recently, Christians have sought to apologise for the horrors of the Crusades but the horrors were on both sides. Indeed, the Crusades must be understood in the context of what Professor Prabhu Guptara calls the 'Crescentades'. Within a hundred years of Muhammad's death all of North Africa was under Muslim rule.

By 1095 when Alexius Comnenus, the Byzantine Emperor, wrote to Pope Urban II asking for help, Muslim armies were also threatening the Western borders of the Byzantine Empire. Islam was an expansionist faith and, though it is certainly the case that it often treated those of other faiths with tolerance, they were always second-class citizens.

We might argue that Christians must take responsibility for their own sin, without necessarily requiring the other to repent. In our current context, however, the failure to acknowledge the excesses of mediaeval Islam is to allow Muslims to cast Christians in the role of long-term imperialist, anti-Islamic oppressor, consistent with the way many millions of Muslims regard the West today. The Crusades, however, were for centuries virtually absent from the popular consciousness of Muslims, but they now serve as what crusade historian, Christopher Tyermanregards as a bogus but convenient proof of a consistent, deep-rooted, religiously motivated attempt to suppress Islam.

Scott's optimism about the future also assumes that Islam is easily cast as a religion of peace. This is by no means clear in the Qur'an. The natural reading of the texts relating to other faiths leads to the opposite conclusion. As Riddell and Cotterell suggest in their helpful book Islam in Conflict, (IVP, 2003),one of the urgent and vital tasks facing moderate Muslims is the hugely difficult one of discerning principles behind Muhammad's responses to 7th century situations that can lead away from the propensity to conflict inherent in the natural, literal readings. As indeed Christians have had to with the difficult war texts in for example, the book of Joshua.

Other commentators accept the gravity of the hermeneutical task but see the key to substantive progress lying in the separation of mosque and state. Once Muslims are genuinely free to choose their religion without fear of reprisal or loss of opportunity, property or life, then we may see the flight of Muslims away from Islam, particularly in the non-Middle eastern states where the Arab-Israeli conflict does not so complicate the issues.

Clearly, in a climate of anxiety for Muslims in the UK, Christians need to be careful not to demonise either our fellow-citizens or indeed Muslims from other countries. On the contrary, we must stand with them and work hard to break down the racism that persists - the average Asian with a University degree finds it harder to get a job than a white person with an 'A' level. Furthermore, on many ethical and social issues, Muslims are our allies - in their respect for the sanctity of life, in their concern for faith-friendly education and faith-friendly workplaces, and in their revulsion at moral decadence and materialism.

Islam, however, is an enthusiastically proselytising religion that denies the resurrection and divinity of Christ, and the reliability and divine inspiration of the Bible. Islam is, in Biblical terms, idolatry. As such, it is a barrier to true human liberation and eternal life. Furthermore, in many, many countries in the world Muslims actively limit freedom of religion, persecute Christians and infringe the human rights of their citizens. Of course, there are moderate Muslims but their existence should not blind us to the reality that they too need Christ.

There was never any blessing to be received in killing an infidel nor is there any blessing today to be had by withholding the only news that will prevent our neighbours' eternal death. In a politically correct, religiously touchy society we are nevertheless called to show and share the kingdom of heaven in our love for our Muslim neighbours and to take up our cross to be peace-makers and peace-bringers. Whatever the cost. Am I ready?