34 A new commandment I give to you, That ye love one another; as I have loved you, that ye also love one another.
35 By this shall all men know that ye are my disciples, if ye have love one to another.
John 13.34-35

More examples could be given, but these are sufficient to establish a background against which we may view the Crusades, which were warfare of a carnal, rather than spiritual, nature, and did not fulfill the commandments of Christ.

To enter upon a detailed history of the Crusades of the Papacy is beyond the scope of this website. Others have already done a very good job of it, and where their work is excerpted here, links are provided. The purpose here is but to show that the papacy was not, in summoning the Crusades, yielded to the Holy Spirit, neither acting as a representative of Christ, nor fulfilling the mission of the Christian Church.

... Rome had founded her dominion upon the dogma of persecution. She sustained herself "Lord of the conscience." Out of this prolific but pestiferous root came a whole century of fulminating edicts, to be followed by centuries of blazing piles.... Divine mistress of the conscience and of the faith, she claimed the exclusive right to prescribe to every human being what he was to believe, and to pursue with temporal and spiritual terrors every form of worship different from her own, till she had chased it out of the world. The first exemplification, on a great scale, of her office which she gave mankind was the crusades. As the professors of an impure creed, she pronounced sentence of extermination on the Saracens of the Holy Land; she sent thither some millions of crusaders to execute her ban; and the lands, cities, and wealth of the slaughtered infidels she bestowed upon her orthodox sons. If it was right to apply this principle to one pagan country, we do not see what should hinder Rome—unless indeed lack of power—from sending her missionaries to every land where infidelity and heresy prevailed, emptying them of their evil creed and their evil inhabitants together, and re-peopling them anew with a pure race from within her own orthodox pale.
The History of Protestantism, Volume First - Book First, Chapter 9, by James A. Wylie

While the Crusades are generally understood to span about two hundred years time from near the end of the eleventh to the late thirteenth century, the beginnings of the papal military mindset had roots in an earlier age. As early as Gregory I ('the Great', bishop of Rome 590-604), military force was viewed by the 'pope' as an acceptable method of performing 'missionary' work.

Gregory, however, thought about missions in terms that were not always consistent with the monastic ideal of conversion by peaceful persuasion. He sometimes advocated a war of aggression against heathens in order to christianize them. His letter to Gennadius, the Byzantine governor from Africa, with the demand "to wage numerous wars"—in complete opposition to his peace efforts in Italy—in order to convert the subjugated to Christianity, can be viewed as the earliest conception of a crusade, a "holy war" differing from the spiritual battles of missionary activities. Gregory became, according to some misrepresentations, the model for the warring Pope Gregory VII (c. 1025-1085) as well as for Anselm of Lucca (Pope Alexander II) and Bonizone of Sutri, the well-known war theorists and contemporaries of Gregory VII. The earliest war benediction originated with Gregory; he has become, along with St. Augustine (354-430), a precedent setter for the ecclesiastical war ideology of the Middle Ages. He admonished Brunhild to prevent pagan sacrifices by means of armed forces.
Copyright © 1994-2000 Encyclopædia Britannica, Inc., Gregory I, Saint: Missions

As the Lord hath made your Excellency to shine with the light of victories in the military wars of this life, so ought you to pose [sic, oppose?] the enemies of the Church with all activity of mind and body, to the end that from both kinds of triumph your reputation may shine forth more and more, when in forensic wars, too, you firmly resist the adversaries of the Catholic Church in behalf of the Christian people, and bravely fight ecclesiastical battles as warriors of the Lord. For it is known that men heretical in religion, if they have liberty allowed them to do harm (which God forbid), rise strenuously against the catholic faith, to the end that they may transfuse, if they can, the poison of their heresy to the corrupting of the members of the Christian body. For we have learnt that they are lifting up their necks against the Catholic Church, the Lord being opposed to them, and desire to pervert the faith of the Christian profession. But let your Eminence suppress their attempts, and subdue their proud necks to the yoke of rectitude....
Epistles of Saint Gregory the Great, Book I, Epistle LXXIV. To Gennadius, Patrician and Exarch of Africa

These carnal wars were not of a spiritual nature for the advancement of the Kingdom of God, but of a political nature for the advancement of the papacy:

The idea of the crusade corresponds to a political conception which was realized in Christendom only from the eleventh to the fifteenth century; this supposes a union of all peoples and sovereigns under the direction of the popes. All crusades were announced by preaching. After pronouncing a solemn vow, each warrior received a cross from the hands of the pope or his legates, and was thenceforth considered a soldier of the Church....
New Advent Catholic Encyclopedia, Crusades, Introduction, ¶ 3

The idea of such a movement was not born at the close of the eleventh century. Gregory VII ... urged the cause upon all Christians, and summoned them to go to the rescue of the Byzantine capital.... His ulterior hope was the subjection of the Eastern churches to the dominion of the Apostolic see....
History of the Christian Church, by Philip Schaff, Volume V, Chapter 7, § 49

Princes and emperors embarked on the Crusades, but these great expeditions, by empowering princes at the heads of armed contingents and by quickening a mass devotion to the cause of the Church as the popes defined it, undercut emperors and boosted popes, leaving a legacy in Germany of a weak monarchy. thus the Crusades, launched by Urban II twenty years after Canossa, had been an opening salvo in a campaign for papal power that would culminate in the claims of Innocent III (1198—1216).
Constantine's Sword, by James Carroll, p 280, Copyright © 2001 by James Carroll