Modern history's judgment on the Crusades has been severe and myopic, set as it is on portraying this glorious episode of Christian history as morally evil. When I praise the Middle Ages, I sometimes have young Catholics defiantly respond, "All right, all right. But how do you justify the Crusades?" Indoctrinated by revisionist history books and inter-religious study courses, they have accepted the false verdict that the Crusades were nothing more than a condemnable act of intolerance in the name of God.
Further, many of these youth have been adversely influenced by innumerable apologies for the Crusades from so many high-placed Catholic Prelates, religious, and educators of the post-Vatican II progressivist Church. Let me give only a few examples:
During a visit to Syria this year, Pope John Paul II himself visited a mosque and asked forgiveness of the Muslims "for Christian offenses and violence of the past."  1. Unease exists within the Church itself over the constant apologies of the Pope for the Church. In its article on the papal apology, The Christian Science Monitor reports, "Commentator Vittorio Messori wrote in yesterday's prestigious Corriere della Sera daily, that there is a part of the Roman Curia that says, John Paul II is distorting the past of the Church, is risking exposing it to humiliations, is paying his respects to its persecutors, is interpreting ecumenism as syncretism, in which one religion seems to be as good as any other." Richard L. Wentworth, "Pope on a mission of contrition," The Christian Science Monitor, May 8, 2001.
On July 15, 1999, the 900th anniversary of the fall of Jerusalem to the Crusaders, a party of Christians, claiming to be acting in the name of Christ and as supposed descendants of Crusaders, paraded round the wall of the Old City to publicize a personal apology to Muslims for the Crusades. 
2. "An Apology, 900 years in the making," Christianity Today, September 6, 1999.
This small incident says a lot: A new Catholic high school in San Juan Capistrano [CA] chose the team name Crusaders, only to have the name vetoed by the board because "it would be offensive to Muslims, who were targets of the bloody crusades of the Middle Ages." 
3. "Crusaders Lose before Joining Battle," Los Angeles Times, June 26, 2001, 86.
To accept blame when one is at fault is, of course, good. But in the above cases, the apologizers and reconciliators only show that they have misinterpreted history.
First, they do not understand what motivated the West to a just war: The crusades were waged to recover the Holy Sepulcher, which had become the target of constant profanation by the Muslims, for the defense of Christian pilgrims, and for the recovery of Christian territory. They constituted a defensive reaction against the Islamic threat.
Second, they do not understand the aggressive nature and fanaticism of Islam [founded by Mohammed, who lived from about 570 to 632 A.D.], which had been in conflict with Christianity since the Muslim conquests of the 7th Century, and had as its goal the imposition of its religion and Mohammedan law on all Europe.
The anger, frustration and fear roused in all Americans at the September 11 attack on the East Coast provide an opportunity to make the Crusades more comprehensible. There are surprising parallels between the two events. Both then and now, there were I) the peril of losing valuable religious principles, such as freedom of worship; 2) a perceived physical threat to fellow countrymen; 3) the injury experienced at losing a landmark site; 4) the sense that what is at stake is nothing less than the survival of Western civilization.
Those who rant and rave against the Crusades may soon find the ground shifting beneath them as they share in a new consensus, which, at base, is not so different from that which supported the medieval religious war they are condemning. Today's call for a war on moral grounds is not so different from that of the Pope who called on Christians throughout Europe to come to the defense of Christendom "out of love of God and their neighbor."  4. Jonathan Riley-Smith, What were the Crusades? [London, 1977], pp. 13-14.
A Threat to Fellow Christians
Since the 3rd Century , a favorite site of pilgrimage for Christians was the Holy Land. When Islam burst out of Arabia and took control of the Middle East in the 7th Century, pilgrimages to the Holy Land became more difficult, but never ceased.
But the great age of pilgrimage began with the 10th Century. In Palestine, the most beloved site of pilgrimage, the lot of the Christians was no longer so bad, and men and women of every class and age, sometimes traveling in parties numbering thousands, journeyed by sea or the land route to visit "the Sepulchre of the Lord which is in Jerusalem." The Fatimid Arabs who were governing Palestine were lenient, trade was prospering, and pilgrims were welcomed for the wealth they brought to the province.
This period of relative peace came to an abrupt halt at the end of the 12th Century. The Arabs were displaced as governors of the holy places by the Seljuk Turks, who reinvigorated the dwindling military spirit of Islam, and again made the call for jihad, or holy war. Their aim was the same as it has been since the inception of Islam, which does not mean "peace," despite the strange and insistent claims of this seen in the newspapers today.
In fact, the word Islam means submission, and not just a passive submission to the book of Islam, the Koran. Submission for the followers of Mohammed means to carry out the will of Allah in history. [Emphases by the web master.] The Muslim doctrine of the jihad, or holy war, stemmed from the ideas of the prophet himself------that is, that it was Allah's will for a permanent war to reign until the rule of Islam extended over all the world: Hence Islam's political domination could be, and was, spread by the sword. This is why Hilaire Belloc predicted almost a century ago that the West could again see a threat from Islam: "It very nearly destroyed us. It kept up the battle against Christendom actively for a thousand years, and the story is by no means over; the power of Islam may at any moment re-arise."  5. Hilaire Belloc, The Great Heresies, Chapter Four.
But, back to the history. By, the Second half of the 12th Century, the Turks had brandished the sword and were creating considerable hardships for Western pilgrims in the East. Travel was no longer safe for Christian pilgrims without an armed escort, and even then, Christians who managed to return to the West had dreadful tales of persecution to tell.
When the call for a Crusade was finally was finally made by Blessed Pope Urban II at Clermont in 1095, he stressed the outrages suffered by fellow Christians at the hands of the militant Muslims:
"They [the Muslim Turks] have invaded the lands of those Christians and have depopulated them by the sword, pillage and fire; they have led away a part of the captives into their own country, and a part they have destroyed by cruel tortures . . . They circumcise the Christians, and the blood of the circumcision they either spread upon the altars or pour into the vases of the Baptismal font.
"When they wish to torture people by a base death, they perforate their navels, and dragging forth the extremity of the intestines, bind it to a stake; then with flogging they lead the victim around until the viscera having gushed forth, the victim falls prostrate upon the ground. Others they bind to a post and pierce with arrows. Others they compel to extend their necks and then, attacking them with naked swords, attempt to cut through the neck with a single blow. What shall I say of the abominable rape of the women? To speak of it is worse than to be silent . . . On whom therefore is the labor of avenging these wrongs and of recovering this territory incumbent, if not upon you?"  6. Dana C. Munro, "Urban and the Crusaders", Translations and Reprints from the Original Sources of European History, Vol. 1 :2, [Philadelphia: University of Pennsylvania, 1895], pp. 5-8.
Such descriptions raised the indignation of the multitudes and inspired an inevitable response. The general view was that the Crusade was justified as a defensive reaction to injuries sustained by the faithful in consequence of past or present aggressions. The Crusaders were protecting the right and possibility of pilgrims to go to the Holy Land.