We have all heard it before, the attacks leveled against the Catholic Church and the crusades. Here is a proper response for those hecklers. Looking at the damage being done by Islam now in western society, it may be a good time to reflect on the past.
1. We might refrain from treating this question of the Crusades.  We have only to read an impartial history to find the justification of these warlike expeditions which exhibit Christian society in all the splendor of religious heroism. Let us observe, however, that the end or motive of the Crusades was perfectly just, and that, so far from having the disastrous effects sometimes attributed to them, they were productive of the happiest results.
A. The Crusades had an end which was just, generous, and civilizing. Mohammed had inspired his followers with the ardor of proselytizing by the sword. Their fanaticism had conquered Spain and, though arrested by the valiant sword of Charles Martel, meditated the conquest of the East and the destruction of civilization. The Emperors of Constantinople appealed to the Christians of the East to protect the last bulwark of Europe, and the Church added her exhortation to this pressing appeal. After Sylvester II and Sergius IV had made a generous appeal in behalf of the Christians of the Holy Land, St. Gregory VII wrote to the Emperor in 1074: "The Christians beyond the sea who are suffering unheard-of outrages, and are daily massacred like sheep, have sent to me in their great need, beseeching me to help our brethren by every means in my power in order that the Christian religion may not, God forbid, be completely annihilated in our time."
In answering the appeal made by Urban II and Peter the Hermit in the Council of Clermont (1095) the Christian princes felt confident they were obeying the will of God. Hitherto they had only defended themselves; now they decided to carry the war into the heart of Islamism, which it was their right and their duty to do, for all the religious and social rights of European nations were threatened by the Mohammedans. Was Europe to await quietly the shame and scourge of slavery; was every Christian nation to allow itself to be oppressed, instead of forming with all the others a holy league against the enemies of the Cross? "When we blame these enterprises," says the learned de Guignes in the Memoires de l'Academie des inscriptions et des belles-lettres (t. lxviii.), "it is because we have not sufficiently reflected upon the state of the times. The Mussulmans had taken possession of Syria, and had made themselves masters of Africa, of Spain, and of all the islands of the Mediterranean, whence they continually insulted the inhabitants on the shores of Italy. Through Spain and Corsica they entered and ravaged the southern provinces, and pillaged all the vessels they encountered. Constantinople was a powerful barrier to them; should they succeed in their attempt against it, all Europe would be endangered and run the risk of falling into their power. Attacking them in the centre of their empire would reduce their strength and deal them a blow from which they could never recover."
B. The Crusades, it is true, did not completely accomplish the end for which they were undertaken, but we may say with Count de Maistre, "Though each one failed, yet all succeeded." To judge these vast enterprises we must take them as a whole, without stopping at the abuses and faults which are the result of human passions, and which are to be found in all wars. Mgr. Pie, in the panegyric on St. Louis, enumerates among the happy results of the Crusades: 1st. The Moslem conquest of Constantinople and the subjugation of the East retarded four hundred years.
2d. The saving of the West and of Christian civilization from the brutalizing rule of Islamism. The Ottoman power, which for centuries threatened to swallow up everything, was so weakened and received such a mortal blow that it continued to exist only through the indulgence of Christianity.
3d. The people of Europe were delivered from the evils which they brought upon themselves by the dissension and incessant wars of prince with prince, lord with lord, city with city. The passion for combats with which the knights were filled found noble vent: ceasing to fight among themselves, Christian warriors united their efforts against the common enemy.
4th. The condition of the people was improved; serfs and vassals were freed by thousands; the commons acquired rights and privileges which curbed the arbitrary and tyrannical power of the lords.
5th. Agriculture, science, and the arts also reaped great advantages. Who does not know that these expeditions paved the way for the beautiful age of Leo X and Louis XIV?
6th. They were likewise productive of much spiritual good. "Can the Christian," exclaims Mgr. Pie, "confine his gaze to the present and forget the grand horizon which opens beyond the tomb? Ah! what matters it to me, a man of the next life, what matters it to me that the Crusades are judged wrong according to the cold and tardy computations of our modern calculators, when the holy Abbot of Clairvaux assures me that he learned from Heaven that this employment of the mammon of iniquity secured to thousands of Frenchmen the imperishable treasures of supreme beatitude?
The losses of the terrestrial country were soon forgotten, and the heavenly country was enriched forever. Men of time, you speak to me of numbers; and I, a priest of eternity, I know but one number which interests me and which is worthy of my attention, the eternal number of the elect." All these advantages largely compensated for the checks which the Crusaders suffered in consequence of dissensions and rivalries among themselves and the perfidy of the Greeks.
From CHRISTIAN APOLOGETICS: A DEFENSE OF THE CATHOLIC FAITH
Fr. W. Devivier, SJ
Edited by Bishop S.G. Messmer, DD, DCL
Bishop of Green Bay, Wisc.
BENZIGER BROTHERS, 1903