[4] Carafa was appointed bishop of Chieti, but resigned in 1524 in order to found with Saint Cajetan the Congregation of Clerics Regular (Theatines).

Carafa was elected pope in 1555 through the influence of Cardinal Alessandro Farnese in the face of opposition from Charles V, Holy Roman Emperor.

In spite of his advanced age, he was a tireless worker and issued new decrees and regulations daily, unrelenting in his determination to keep Protestants and recently immigrated Marranos from gaining influence in the Papal States.

Paul IV issued the Papal bull Cum nimis absurdum, which confined Jews in Rome to the neighbourhood claustro degli Ebrei ("enclosure of the Hebrews"), later known as the Roman Ghetto.

Under the direction of Pope Leo X, he was ambassador to England and then papal nuncio in Spain, where he conceived a violent detestation of Spanish rule that affected the policies of his later papacy.

As pope, Paul IV's nationalism was a driving force; he used the office to preserve some liberties in the face of fourfold foreign occupation.

His treatment of Giovanna d'Aragona, who had married into that family, drew further negative comment from Venice because she had long been a patron of artists and writers.

[7] Paul IV was displeased at the French signing a five-year truce with Spain in February 1556 (in the midst of the Italian War of 1551–1559) and urged King Henry II of France to join the Papal States in an invasion of Spanish Naples.

On 1 September 1556, King Philip II responded by preemptively invading the Papal States with 12,000 men under the Duke of Alba.

Out of fear of another sack of Rome, Paul IV agreed to the Duke of Alba's demand for the Papal States to declare neutrality by signing the Peace of Cave-Palestrina on 12 September 1557.

[10] Carlo's older brother Giovanni was made commander of the Papal forces and Duke of Paliano after the pro-Spanish Colonna were deprived of that town in 1556.

At the time of Paul's election, Queen Mary I of England was two years into her reign, and was rolling back the English Reformation that had occurred under her half-brother Edward VI.

Paul IV issued a papal bull in 1555, Ilius, per quem Reges regnant, removing all Church measures against the English government, and further recognising Mary and her husband Philip as King and Queen of Ireland, rather than merely being "lord".

[2] Paul IV was violently opposed to the liberal Cardinal Giovanni Morone, whom he strongly suspected of being a hidden Protestant, so much that he had him imprisoned.

The strengthening of the Inquisition continued under Paul IV, and few could consider themselves safe by virtue of position in his drive to reform the Church; even cardinals he disliked could be imprisoned.

The Pope set its borders near the Rione Sant'Angelo, an area where large numbers of Jews already resided, and ordered it walled off from the rest of the city.

[14] Yet his anti-Jewish legacy endured for over 300 years: the ghetto he established ceased to exist only with the dissolution of the Papal States in 1870.

[citation needed] According to Leopold von Ranke, a rigid austerity and an earnest zeal for the restoration of primitive habits became the dominant tendency of his papacy.

Paul IV put in place a reform of the papal administration designed to stamp out trafficking of principal positions in the Curia.

But Paul IV (1555–59), the voice of the Counter-Reformation, dealt them an irreparable blow when he withdrew the protections previously given and initiated a campaign against them.

[19][20] Throughout his pontificate, Paul IV named 46 cardinals in four consistories, including Michele Ghislieri (the future Pope Pius V).

In response, Father Pedro de Ribadeneira repeated what the saint had said to him: "If our Lord does not lay down his hand, we will have Master Laínez a cardinal, but I certify to you, if it were, that it be with so much noise that the world would understand how the Society accepts these things".

Cardinals and other officials gathered at his bedside on 18 August, where Paul IV asked them to elect a "righteous and holy" successor and to retain the Inquisition as "the very basis" of the Catholic Church's power.

His anti-Spanish feelings alienated the Habsburgs, arguably the most powerful Catholic rulers in Europe, and his ascetic personal beliefs left him out of touch with the artistic and intellectual movements of his era (he often spoke of whitewashing the Sistine Chapel ceiling).

Such a reactionary attitude alienated clergy and laity alike: historian John Julius Norwich calls him "the worst pope of the 16th century.

[28] In the novel Q by Luther Blissett, while not appearing himself, Gian Pietro Carafa is mentioned repeatedly as the cardinal whose spy and agent provocateur, Qoelet, causes many of the disasters to befall Protestants during the Reformation and the Roman Church's response in the 16th century.

[citation needed] Pope Paul IV is a major villain in Sholem Asch's 1921 historical novel The Witch of Castile (Yiddish: Di Kishufmakherin fun Kastilien, Hebrew: Ha'Machshepha Mi'Castilia המכשפה מקשיטליה).