The Catholic Church in Spain has a long history, starting in the 1st century AD. It is the largest religious group in the country, with 58.6% of Spaniards identifying as "Catholic".CIS."Barómetro de Julio de 2021", 3,814 respondents. The question was "¿Cómo se define Ud. en materia religiosa: católico/a practicante, católico/a no practicante, creyente de otra religión, agnóstico/a, indiferente o no creyente, o ateo/a?".

Attempts were made from the late 1st century to the late 3rd century to establish Christianity in the Iberian Peninsula. Paul the Apostle expressed a wish to preach in Spain in the Epistle to the Romans; Clement of Rome writes in his Epistle to the Corinthians that Paul "travelled as far as the extremity of the West," and the Muratorian Canon also speaks of Paul having departed from Rome for Spain. Although most scholars of early Christianity believe Paul did not make an actual journey to Spain after writing the Epistle to the Romans, Jerome Murphy-O'Connor holds that Paul did travel to Spain and preach there for up to a few months with little success, most likely because Greek was not widely spoken there. Timothy D. Barnes suggests that Paul's trial and execution took place not in Rome as traditionally believed, but under a provincial governor in Spain. Traditional accounts credit the Apostle James the Great with early preaching of the Christian faith in Spain.

Canons of the Synod of Elvira (circa 305 AD in Rome) indicate that the church was greatly isolated from the general population even at that time. The situation of the Christians in Iberia improved with the advent of the Edict of Milan in 313 AD, after which Christians were more or less free to openly practice their new religion within the Roman Empire. Over the course of the 4th century, the church built significant footholds, particularly around Barcelona, Córdoba, Seville, and Toledo.

Visigoths As Rome declined, Germanic tribes invaded most of the lands of the former empire. In the years following 410 Spain was taken over by the Visigoths who had been converted to Arian Christianity around 419. The Visigothic Kingdom established their capital in Toledo, their kingdom reaching its high point during the reign of Leovigild. Visigoth rule led to the expansion of Arianism in Spain. In 587, Reccared, the Visigothic king at Toledo, was converted to Catholicism and launched a movement to unify doctrine (see the Unidad católica de España). The Council of Lerida in 546 constrained the clergy and extended the power of law over them under the blessings of Rome.

Councils of Toledo

About thirty synods, variously counted, were held at Toledo in what would come to be part of Spain. The earliest, directed against Priscillianism, assembled in 400. The "third" synod of 589 marked the epoch-making conversion of King Reccared from Arianism to the Nicene Creed. The "fourth", in 633, probably under the presidency of the noted Isidore of Seville, regulated many matters of discipline and decreed uniformity of liturgy throughout the kingdom. The British Celts of Galicia accepted the Latin rite and stringent measures were adopted against baptized Jews who had relapsed into their former faith. The "twelfth" council in 681 assured to the archbishop of Toledo the primacy of Hispania (present Iberian Peninsula). As nearly one hundred early canons of Toledo found a place in the Decretum Gratiani, they exerted an important influence on the development of ecclesiastical law.

The seventh century is sometimes called, by Spanish historians, the Siglo de Concilios, or "Century of Councils".

Muslim occupation and the reconquest (8th–15th centuries)

By 689, Arabs and Berbers conquered Melilla, and by 709, Ceuta was taken. By 711, Islam dominated all the north of Africa. The process of islamization of the Berber tribes had begun, though most of the population was still Christian, Jew or polytheist. A raiding party recruited mostly among these newly subjugated, still non-Muslim Berbers and led by convert Tariq ibn-Ziyad was sent to plunder the south of the Visigothic Kingdom of Spain, which faced strong internal tensions and was at the verge of a civil war between the Chindasvintan, Witizan and nobiliary parties. Crossing the Strait of Gibraltar, it won a decisive victory in the summer of 711 when the Visigothic king Roderic was betrayed by the Witizan wings of his army and killed on 19 July at the Battle of Guadalete. Roderic's body was never found, and many rumors about his fate arose, which led to a paralysis on the Visigothic command. Tariq's commander, Musa bin Nusair, quickly crossed with substantial Muslim reinforcements from the Caliphal garrison of North Africa and by 718 the Muslims dominated most of the peninsula. The advance into Europe was stopped by the Franks under Charles Martel at the Battle of Tours in 732.

The rulers of Al-Andalus were granted the rank of Emir by the Umayyad Caliph Al-Walid I in Damascus. After the Umayyads were overthrown by the Abbasids, some of their remaining leaders escaped to Spain under the leadership of Abd-ar-rahman I who challenged the Abbasids by declaring Córdoba an independent emirate. Al-Andalus was rife with internal conflict between the Arab Umayyad rulers, the north-African Berbers who had formed the bulk of the invasion force, and the Visigoth-Roman Christian population that was a majority for almost the next four centuries.

In the 10th century, Abd-ar-rahman III declared the Caliphate of Córdoba, effectively breaking all ties with the Egyptian and Syrian caliphs. The Caliphate was mostly concerned with maintaining its power base in North Africa, but these possessions eventually dwindled to the Ceuta province. Meanwhile, a slow but steady migration of Christian subjects to the northern kingdoms was increasing the power of the northern kingdoms.

Al-Andalus coincided with La Convivencia, an era of religious tolerance (as far as Christians and Jews peacefully accept submission to Muslims, as well as being reduced to the condition of tax-paying serfs) and with the Golden age of Jewish culture in the Iberian Peninsula (912, the rule of Abd-ar-Rahman III. to 1066, Granada massacre).Granada by Richard Gottheil, Meyer Kayserling, Jewish Encyclopedia. 1906 ed.

Medieval Spain was the scene of almost constant warfare between Muslims and Christians. The Almohads, who had taken control of the Almoravids' Maghribi and Andalusian territories by 1147, far surpassed the Almoravides in fundamentalist outlook, and they treated the dhimmis harshly. Faced with the choice of death, conversion, or emigration, many Jews and Christians left.The Almohads

Reconquista

Expansion into the Crusades In the High Middle Ages, the fight against the Moors in the Iberian Peninsula became linked to the fight of the whole of Christendom. The Reconquista was originally a mere war of conquest. It only later underwent a significant shift in meaning toward a religiously justified war of liberation (see the Augustinian concept of a Just War). The papacy and the influential Abbey of Cluny in Burgundy not only justified the anti-Islamic acts of war but actively encouraged Christian knights to seek armed confrontation with Moorish "infidels" instead of with each other. From the 11th century onwards indulgences were granted: In 1064 Pope Alexander II promised the participants of an expedition against Barbastro a collective indulgence of 30 years, before Pope Urban II called the First Crusade. Not until 1095 and the Council of Clermont did the Reconquista amalgamate the conflicting concepts of a peaceful pilgrimage and armed knight-errantry.

But the papacy left no doubt about the heavenly reward for knights fighting for Christ (militia Christi): in a letter, Urban II tried to persuade the reconquistadores fighting at Tarragona to stay in the Peninsula and not to join the armed pilgrimage to conquer Jerusalem since their contribution for Christianity was equally important. The pope promised them the same rewarding indulgence that awaited the first crusaders.

Inquisition

After centuries of the Reconquista, in which Christian Spaniards fought to drive out the Moors, the Spanish Inquisition was established in 1478 by Catholic Monarchs Ferdinand II of Aragon and Isabella I of Castile, to complete the religious purification of the Iberian Peninsula.

It was intended to maintain Catholic orthodoxy in their kingdoms, and to replace the Medieval Inquisition which had been under papal control. The new body was under the direct control of the Spanish monarchy.

The Inquisition, as an ecclesiastical tribunal, had jurisdiction only over baptized Christians, some of whom also practised other forms of faith and at the time were considered heretics according to the Catholic Church and recently formed kingdoms at the time. The Inquisition worked in large part to ensure the orthodoxy of recent converts.

In the centuries that followed Spain saw itself as the bulwark of Catholicism and doctrinal purity.

Alhambra decree

On 31 March 1492, the joint Catholic Monarchs of Spain (Isabella I of Castile and Ferdinand II of Aragon) issued the Alhambra decree, accusing Jews of trying "to subvert their holy Catholic faith and try to draw faithful Christians away from their beliefs" and ordering the expulsion of Jews from the Kingdom of Spain and its territories and possessions by 31 July of that year.

Some Jews were given only four months and ordered to leave the kingdom or convert to Christianity. Under the edict, Jews were promised royal "protection and security" for the effective three-month window before the deadline. They were permitted to take their belongings with them – except "gold or silver or minted money".

The punishment for any Jew who did not leave or convert by the deadline was death. The punishment for a non-Jew who sheltered or hid Jews was the confiscation of all belongings and hereditary privileges.

As a result of this expulsion, Spanish Jews dispersed throughout the region of North Africa known as the Maghreb. They also fled to south-eastern Europe where they were granted safety in the Ottoman Empire and formed flourishing local Jewish communities, the largest being those of Thessaloniki and Sarajevo. In those regions, they often intermingled with the already existing Mizrachi (Eastern Jewish) communities.

Scholars disagree about how many Jews left Spain as a result of the decree; the numbers vary between 130,000 and 800,000. Other Spanish Jews (estimates range between 50,000 and 70,000) chose in the face of the Edict to convert to Christianity and thereby escape expulsion. Their conversion served as poor protection from church hostility after the Spanish Inquisition came into full effect; persecution and expulsion were common. Many of these "New Christians" were eventually forced to either leave the countries or intermarry with the local populace by the dual Inquisitions of Portugal and Spain. Many settled in North Africa or elsewhere in Europe, most notably in the Netherlands and England.

Spanish Empire Spanish missionaries carried Catholicism to the New World and the Philippines, establishing various missions in the newly colonized lands. The missions served as a base for both administering colonies as well as spreading Christianity.

However, the Spanish kings insisted on these missions maintaining independence from papal "interference"; bishops in Spanish domains were forbidden to report to the Pope except through the Spanish crown.

16th century Philip II became king on Charles V's abdication in 1556. Spain largely escaped the religious conflicts that were raging throughout the rest of Europe, and remained firmly Roman Catholic. Philip saw himself as a champion of Catholicism, both against the Ottoman Turks and the heretics.