At last month's National Prayer Breakfast in Washington DC, US President Barack Obama reignited a thousand year old debate with his comments about the Crusades.
While looking back at the death and destruction ISIS has meted out over the last year, President Obama cautioned Christians to not get on a moral "high horse" in their judgment of the religion which produced it.
After all, hadn't the Crusades, the Spanish Inquisition, and slavery (in its American context) all been, at one time or another, conducted and defended in the name of Christ?
Of all the events mentioned the one singled out for the most commentary and debate was the Crusades. Amongst some Christian circles in particular, there appears to be an angry reaction to the idea that the Crusades and ISIS's caliphate could be compared on a similar level morally.
So what were the Crusades? Were they a righteous, just war fought for the protection of the innocent and defenceless? Or a campaign fought by violent extremists of a similar ilk to those in Iraq and Syria at the present time?
The just war
From the very beginning of the First Crusade in 1096, there was amongst theologians and churchmen an urgently felt need to define it as a war which was legitimate and just.
Following the teachings of the great fifth century theologian St Augustine, the scholars of the eleventh century had a fairly clear definition of what constituted a Christian just war. Firstly, it had to be fought for a just cause; either as a defensive war against invasion, or for the recovery of unlawfully taken property. Secondly, it had to be authorised by a legitimate public authority. Finally, it had to be fought with a righteous intent â motivated by a love of God, and neighbour, and without desire for power and domination.
When using these criteria, the motives for crusade in the eleventh century can be considered reasonable on a number of points. While under less threat than in previous decades, Christian Western Europe had essentially been under siege from its enemies for several centuries. Muslim armies had overrun North Africa and much of Spain, and were a constant threat to both France and Italy. In the north, pagan Viking armies had terrorised much of Northern Europe's coastline â although by the eleventh century many had been converted.
Christians in the east were also struggling to stem the invasion from Muslim armies into their homelands. Ostensibly, the whole reason for the First Crusade came in response to a call in 1095 from the Emperor of the Eastern Roman (Byzantine) Empire, Alexios Komnenos, to send military aid to help defend against the invasion of the Seljuk Turks into Asia Minor. Recently converted to Islam, the Seljuks were zealous for their faith. Not only did they take over Byzantine land, but were also severely persecuting the Christians that they now ruled over, as well as Western pilgrims who attempted to travel through their territory.
Indeed, this was how the theologians of the Latin Church would frame their justification for the Crusades. It was a war fought for the defence and liberation of fellow Christians suffering under the persecution of a foreign enemy, and fought by Christian soldiers willing to lay down their lives for the sake of their brethren who could not defend themselves.
The holy war
However, while the Crusades were framed by theologians as a just war, they were also different in a manner which had no real precedent in Christianity prior to that point.
This was not a regular war fought on the authority of a secular ruler â the troops raised would not be given to the command of the Byzantine Emperor as had been requested. Instead, the instigator and leader of the crusading army was none other than the Pope himself, Urban II.
This is highly significant, as according to the understanding of the Roman Church, the Bishop of Rome was the heir to St Peter, and Christ's representative on earth. The soldiers who fought, were in very literal terms considered to be the militia Christi (soldiers of Christ). While on crusade they may have fought under the orders of their secular leaders, ultimately their allegiance was sworn to the Pope.
In return for the soldiers offering their services to the Pope, those who participated in the crusade would be granted an indulgence â offering them a remission of any penance they were required to serve, and giving them absolution of their sins.
For nobles and knights wracked with guilt over the violent deeds that their way of life demanded, it offered, in the words of Guibert of Nogent "a new way of attaining salvation ... Now they can to some degree win God's grace while pursuing their own way of life, with the freedoms and in the dress to which they are accustomed." This represented an almost unheard of development in the Church. Warfare â which had up to that point had been an activity that would under many circumstances be expected to require penance â was now, under the guise of the crusade, considered to be a penitential act in of itself.
With these measures set in place, the stage was now set for a war in the Holy Land which would drag on for nearly 200 years â and would ultimately end in failure.
The Crusades present to us a cautionary tale in Christian history. They are an example to us of what happens when the Church forgets the nature of the Kingdom of God, and the nature of the enemy it struggles against.
They stemmed from an obsession of the Western Church to not only exercise spiritual lordship over its members, but also political lordship. Laying aside the sword of the spirit, which is the word of God, it instead took up a sword of steel. Rather than looking ahead to win souls for citizenship in the New Jerusalem, it focused its attention on capturing the earthly Jerusalem.
While many who participated in Crusades may have had strongly held, sincere convictions that they were doing the will of God, it ultimately represented a major misunderstanding of the gospel and the role of the Church in the world.
Whether there were grounds for a just war at the time or not â it is clear that it was not the kind of war the Church has been commissioned to fight.
Tim Newman lives in Christchurch, New Zealand. He holds an MA in History and is currently working as a ministry intern at Cornerstone Church.