Spain increasingly felt itself besieged on all sides

From Carnage and Culture by Victor Davis Hanson. Page 199.

Christian fanaticism and strict Catholicism were the bedrock defenses of southern Mediterranean cultures besieged by Islamic enemies to the south and east, and the newer Protestant adversaries of northern Europe. Protestant Europeans were far from the front lines of Islamic attack; and, without the strong traditions of adherence to a centralized autocrat in Rome, they might find religious reform an indulgence that beleaguered Italians, Spaniards, and Greeks could not afford. In the era of the conquest of Mexico, Spain increasingly felt itself besieged on all sides. Powerful Jews, through economic might and commercial influence, might exploit and dominate the Catholic peasantry; Protestant fanatics might scour the Spanish countryside, undermining local churches and papal estates; Moors and Ottomans might conspire to return Spain to the Islamic world and thereby overturn the new national creation of Ferdinand and Isabella. In the paranoid Spanish mind the Inquisition and the Reconquista alone had saved Spain, yet the new nation’s continued survival depended on a class of knights who might spread Catholicism to the New World before it, too, was colonized by northern Europeans and its treasures used to further religious strife in the Old World.

Hard, sometimes, to recollect the context behind behaviors that to the modern mind seem so barbaric and pointless.