I’ve dipped into Wikipedia, History.com, Brittanica and the book, The Life and Times of Rodrigo Borgia, by Arnold H. Matthew, to outline the process through which the Popes came into being. I wanted to understand the history of Christianity, the role of the Pope at the time Ferdinand II and his second cousin Isabella I were married, and what characteristics made the Conquistadors so determined and so dismissive of those natives of the New World.

Creation of the Roman Church

Since its inception, the Roman Catholic Church became powerful over 7 centuries during the Middle Ages.The struggles for power between kings and popes shaped the western world.

By the time the Roman Empire fell, the Catholic Church had already been created:

Constantine the Great was born in Naissus, Moesia Superior (modern day Serbia). Constantine was known as the first emperor to claim conversion to Christianity, and was baptised shortly before he died. Emperor Constantine issued the Edict of Milan in 313 proclaiming toleration for the Christian religion, and convoked the First Council of Nicaea in 325 whose Nicene Creed included belief in “one holy catholic and apostolic Church”. 

Emperor Theodosius I , born in Hispania, was a very devout Nicene Christian. Theodosius made Nicene Christianity the state church of the Roman Empire with the Edict of Thessalonica of 380.

When the Roman Empire fell in the 5th century, the Emperors were gone, but the Roman Church remained.
As the influence of the Catholic Church spread over the next 5 centuries, the clergy developed a model of church-state relations which was accepted by various Church and political leaders in European history until its eventual rejection by Martin Luther and Henry VIII.

During the Middle Ages, it was customary to classify the population of Christendom into laboratores (workers), bellatores (soldiers), and oratores (clergy). The last group, though small in number, monopolized the instruments and opportunities of culture, and ruled with almost unlimited sway half of the most powerful continent on the globe. This power created a hierarchy of institutionalised respect from workers and soldiers.

Major events were perpetrated when the Catholic Church’s authority peaked over all European Christians and the common endeavours of the Christian community. Examples include  the Crusades, the ejection of Muslims and Jews from the Iberian Peninsula and the conflict with Muslims of the Ottoman Empire. 

Creation of the institution of Pope

I found that the early popes retained their birth names, but after 533 they chose a new name upon their accession. Names are freely chosen by popes, and are not based on any system. Names of immediate or distant predecessors, mentors, saints, or even family members—as was the case with John XXIII—have been adopted.

Where the person-to be-pope was born was also was a factor, since the most powerful and influential position in Europe was sought by many ambitious families.

The Crusades

First Crusades 1095: Pope Urban II called on Christians from Western Europe to go to war against Muslim forces in the Holy Land. Urban denigrated the Muslims, exaggerating stories of their anti-Christian acts, and promised absolution and remission of sins for all who died in the service of Christ. As nobles and poor alike were usually squabbling, this plea focused their minds and they were inspired by Urban to believe they were to fight a righteous war to help their fellow Christians in the East and to take back Jerusalem. All told, between 60,000 and 100,000 people responded. 

Urban’s war cry caught fire, mobilizing clerics to drum up support throughout Europe for the crusade against the Muslims and to march on Jerusalem. Many European nobles saw their chance to increase land holdings and gain riches from the conquest. These nobles were responsible for the death of a great many innocents both on the way to and in the Holy Land, absorbing the riches and estates of those they conveniently deemed opponents to their cause. Although many of the untrained Christian peasants were hacked to death by professional Muslim soldiers, their superior numbers ensured that the Christians ultimately prevailed.

After the First Crusade achieved its goal with the capture of Jerusalem in 1099, the invading Christians set up several Latin Christian states, even as Muslims in the region vowed to wage holy war (jihad) to regain control over the region.

Deteriorating relations between the Crusaders and their Christian allies in the Byzantine Empire culminated in the sack of Constantinople in 1204 during the Third Crusade. 

Near the end of the 13th century, the rising Mamluk dynasty in Egypt provided the final reckoning for the Crusaders, toppling the coastal stronghold of Acre and driving the European invaders out of Palestine and Syria in 1291.

The fight against the Moors ( see  Overview ) in the Iberian Peninsula:

In 801, Charlemagne captured Barcelona and established Frankish control over the Spanish March, the region between the Pyrenees and the Ebro River. 

Asturian kings, presenting themselves as the heirs to the Visigothic monarchy which had ruled Spain prior to the Muslim conquest, capitalized on dissension within the Moorish ranks and expanded their holdings in the late 9th century. 

There was a resurgence of the Córdoban caliphate and a break between the Christian kingdoms of Castile and León in the 10th century.

Christian lands of northern Spain were briefly united under Sancho III Garcés (Sancho the Great), who greatly expanded the holdings of Navarre. Sancho created the kingdom of Aragon in 1035, and his successors there pursued the Christian reclamation of the peninsula in earnest. 

Alfonso I of Aragon captured the former Moorish capital of Zaragoza in 1118. 

In 1179 Alfonso II of Aragon and Alfonso VIII of Castile concluded the Pact of Cazorla, an agreement whereby the task of reconquering the Moorish kingdom of Valencia was reserved to the Aragonese crown. In exchange, Aragon relinquished all claims to other Moorish-held territory in the peninsula.

After suffering a crushing defeat at the Battle of Alarcos (July 18, 1195) at the hands of the Almohad caliph Abū Yūsuf Yaʿqūb al-Manṣūr, Alfonso VIII appealed to other Christian leaders.

In 1212 he won the support of Pope Innocent III, who declared a Crusade against the Almohads. Supported by the armies of Aragon, Navarre, and Portugal, Castilian forces routed the Almohad emir of Morocco, Muḥammad al-Nāṣir, at Las Navas de Tolosa (July 16, 1212) and so removed the last serious Islamic threat to Christian hegemony in Spain. The way was now open to the conquest of Andalusia.

The last king of León, Alfonso IX, was succeeded upon his death in 1230 by his son, Ferdinand III, who was already king of Castile. Castile and León were thus reunited, and the new sovereign at once embarked on a great series of campaigns to subdue Andalusia.

Those began with:

-the capture of Córdoba (1236) and culminated in 

-the surrender of Sevilla (1248). 

Influenced by the crusading zeal instilled into the Spanish church by the Clunia and Cistercian orders, Ferdinand at first expelled the Moorish inhabitants of the Andalusian cities en masse but was later forced to modify his policy by the collapse of the Andalusian economy that inevitably ensued. 

James I of Aragon completed Aragon’s part in the Reconquest:

– Occupied the Balearics (1235)

– Captured Valencia (1238). 

Unlike Ferdinand, James carefully worked to preserve the agricultural economy of the Moors and so established the final peninsular frontiers of Aragon.

In Portugal, Afonso III captured Faro (1249), the last Moorish stronghold in the Algarve. By the end of the 13th century, the Reconquest was, for all practical purposes, brought to an end. 

The last significant Muslim incursion into Christian Iberia culminated with the Battle of Río Salado (October 30, 1340), where Portuguese and Castilian forces administered a crushing defeat to the armies of Marīnidsultan Abū al-Ḥasan 

The kingdoms of Aragon, Castile, and Portugal spent the next century consolidating their holdings, until the marriage of Ferdinand II of Aragon and Isabella I of Castile in 1469 united the Spanish crown. 

The Catholic Monarchs, as Ferdinand and Isabella came to be known, completed the conquest of Granada in 1492.  In the same year,  on the night of August 10-11, 1492 , the name of Spaniard, Rodrigo Borgia was drawn out of the electoral chalice. At dawn a window of the Conclave was opened and the election of Pope Alexander VI made known…..The news of Borgia’s election excited much displeasure in certain quarters, though we can hardly credit Guicciardini’s assertion that all men were filled with dismay, and that Ferrante of Naples, one of the most keen-sighted rulers of the day, told his wife with tears—tears which he had not shed even at the death of his two sons—“ This election will not only undermine the peace of Italy, but that of the whole of Christendom”.

Many historians believe that the crusading spirit of the Reconquista was preserved in the subsequent Spanish emphasis on religious uniformity, evidenced by the strong influence of the Inquisition and the expulsion of people of Moorish and Jewish descent.

  The Iberian reconquest, which began as a traditional war of conquest, became a crusade against Islam and fused an Iberian Catholicism that Spain and Portugal later transplanted around the globe. In the early 21st century its members represented nearly half of the world’s Roman Catholics. The Crusades (1095–1396) produced among many Christians an adversarial approach to those of other faiths and helped to develop a sense of communal identity against the obstacle of Europe’s deep political divisions. (Brittanica)