Al-Maqdisi observes of the Khurramites that "the basis of their doctrine is belief in light and darkness"; more specifically, "the principle of the universe is Light, of which a part has been effaced and has turned into Darkness".

They "avoid carefully the shedding of blood, except when they raise the banner of revolt".

They are "extremely concerned with cleanliness and purification, and with approaching people with kindness and beneficience".

Some of them "believed in free sex, provided that the women agreed to it, and also in the freedom of enjoying all pleasures and of satisfying one's inclinations so long as this does not entail any harm to others". (Their name is most frequently derived from the Persian word khurram "happy, cheerful" ).

Regarding the variety of faiths, they believe that "the prophets, despite the difference of their laws and their religions, do not constitute but a single spirit".

Naubakhti states that they also believe in reincarnation (metempsychosis) as the only existing kind of afterlife and retribution and in the cancellation of all religious prescriptions and obligations.

They highly revere Abu Muslim and their imams.

In their rituals, which are rather simple, they "seek the greatest sacramental effect from wine and drinks".

As a whole, they were estimated by Al-Maqdisi as "Mazdaeans... who cover themselves under the guise of Islam".

The merciless civil war among the Abbasids entails severe persecution for non-Muslims.

Al-Muqanna‘ was instrumental to the formation of the Khurramiyya, a communistic sect that claims Abū Muslim to be the Mahdi and denies his death.

Under the leadership of Bābak, the Khurammites proclaim the breakup and redistribution of all the great estates and the end to despotic foreign rule.

Taking advantage of the turmoil created by the Abbasid civil war, in 816 they began making attacks on Muslim forces in Iran and Iraq.

Leo III, having renovated and beautified the churches in Rome during his pontificate, dies in 816.

His replacement, the son of a Roman noble called Marinus, belongs to the same family that produced the Popes Sergius II and Adrian II.

At a young age he was raised at the Lateran Palace during the pontificate of Pope Adrian I, and it was under Stephen's predecessor Pope Leo III that he was first ordained a Subdeacon before he was subsequently made a Deacon.

Very popular among the Roman people, within ten days of Leo III’s death, he is escorted to Saint Peter’s Basilica and consecrated Bishop of Rome on June 22, 816, as Stephen IV.

His rapid election may have been an attempt by the Roman clergy to ensure that the Roman emperor could not interfere in the election.

Immediately after his consecration he orders the Roman people to swear fidelity to the Frankish king and Roman emperor Louis the Pious, after which Stephen sends envoys to the emperor notifying him of his election, and to arrange a meeting between the two at the emperor’s convenience.

Bernard is the illegitimate son of King Pepin of Italy, the second legitimate son of the Emperor Charles.

Despite his status, Charles had allowed him to inherit Italy after the death of Pepin in 810.

Bernard married a woman named Cunigunde, but the year of their marriage, and her origins are obscure; spuriously she has been called "of Laon".

They have one son, Pepin, Count of Vermandois.

Bernard is a trusted agent of his grandfather, and of his uncle.

His rights in Italy are respected, and he is used as an intermediary to manage events in his sphere of influence—for example, when in 815 Louis the Pious receives reports that some Roman nobles had conspired to murder Pope Leo III, and that he had responded by butchering the ringleaders, Bernard had been sent to investigate the matter.

Stephen, with Louis’ invitation, leaves Rome in August 816, crossing the Alps together with Bernard, the King of the Lombards, who has been ordered to accompany Stephen to the emperor.

The Early Reign of Louis the Pious and the 816 Papal Coronation

Following his accession in 814, Louis the Pious surrounds himself with trusted advisors, continuing some of his father’s ministers while introducing new figures to his court. Among his chief counselors are:

• Bernard, Margrave of Septimania, a powerful noble in southern Gaul.
• Ebbo, Archbishop of Reims, an ambitious churchman born a serf, whom Louis elevates to high office—though he will later betray the emperor.
• Elisachar, Abbot of St. Maximin near Trier, and Hildebold, Archbishop of Cologne, both retained from Charlemagne’s administration.
• Benedict of Aniane, a Visigothic monastic reformer, tasked with strengthening the Frankish Church.

Benedict of Aniane and the Reform of Monastic Life

Benedict of Aniane, often called the Second Benedict, enforces a major religious reform:

• He ensures that all monastic houses in Louis' realm adhere to the Rule of Saint Benedict, originally formulated by Benedict of Nursia (480–550)—the First Benedict.
• This reform standardizes monastic discipline, reinforcing the importance of communal prayer, manual labor, and study as the pillars of monastic life.

The Papal Coronation of Louis the Pious (816)

In October 816, Pope Stephen IV travels north to meet Louis the Pious at Reims, where the emperor prostrates himself three times before the Pope, demonstrating his piety and submission to the Church.

On Sunday, October 5, 816, during Mass, Stephen formally anoints and crowns Louis as emperor, placing on his head a crown claimed to have belonged to Constantine the Great. At the same time, he also crowns Louis’ wife, Ermengarde of Hesbaye, and salutes her as Augusta.

This event serves multiple purposes:

• It reinforces papal authority in the imperial coronation process, especially after Louis had self-coronated in 813 at the behest of Charlemagne.
• It reaffirms the alliance between the Frankish rulers and the papacy, solidifying the Papal States and their privileges.
• It emphasizes that imperial legitimacy is granted not just by heredity or conquest, but also through papal approval.

Diplomatic Agreements and Religious Reforms

While at Louis’ court, Pope Stephen IV secures:

• A land grant, likely at Vendeuvre-sur-Barse, reinforcing the Church’s growing territorial independence.
• The renewal of the Frankish-papal alliance, confirming the privileges of the Roman Church and the continued sovereignty of the Papal States.
• The promotion of Theodulf of Orléans to archbishop, a significant elevation in the Frankish ecclesiastical hierarchy.
• The release of Roman political prisoners, exiled during the turbulent reign of Pope Leo III.

Stephen also urges Louis to enforce reforms among the clergy living under the Rule of Chrodegang, including:

• The strict separation of men and women in religious communities.
• The requirement that monastic property be held in common, ensuring no individual accumulation of wealth.
• Regulations on food and wine consumption, reinforcing a disciplined clerical lifestyle.

The Coronation of 816: A Turning Point in Frankish-Papal Relations

The 816 coronation of Louis the Pious is a significant moment in the history of the Frankish Empire and the papacy. It marks a shift from Charlemagne’s imperial self-reliance to a more church-dependent rule, paving the way for increasing papal influence over the empire’s affairs. This coronation foreshadows the medieval struggles between secular rulers and the papacy, as both seek to define the limits of imperial and ecclesiastical power in Europe.

After visiting Ravenna on his way back from Reims, Stephen had returned before the end of November 816 to Rome, where he apparently discontinued Leo III’s policies of favoring clergy over lay aristocracy.

After holding the traditional ordination of priests and bishops in December and confirming Farfa Abbey’s possessions on condition that every day the monks would recite one hundred “Kyrie Eleisons” as well as a yearly payment to the Roman Church of ten golden solidi, Stephen dies on January 24, 817.

He is buried at St. Peter’s.

At some point, Stephen will be canonized as a saint of the Catholic Church.

The abbot of Santo Stefano Rotondo, Pascale Massimi, a native of Rome and son of Bonosus and Lady Theodora, is raised to the pontificate as Paschal I by the acclamation of the clergy less than a day after the death of Pope Stephen IV.

This decision occurs before the sanction of the emperor Louis the Pious has been obtained, and in a circumstance for which it is one of his first tasks to apologize.

He advises the emperor that the decision had been made to avoid factional strife in Rome, and his papal legate Theodore supposedly returned with a document titled Pactum cum Pashali pontiff, in which the Emperor congratulated Paschal, recognized his sovereignty over the Papal States and guaranteed the free election of future pontiffs.

This document will be challenged by later historians as a forgery as Paschal’s relations with the imperial house are never cordial, and he will have no success in winning the sympathy of the Roman nobles.

Louis and his court are crossing a wooden gallery from the cathedral to the palace in Aachen on Maundy Thursday 817, when the gallery collapses, killing many.

Louis, having barely survived and feeling the imminent danger of death, begins planning for his succession; three months later he issues an Ordinatio Imperii, an imperial decree that lays out plans for an orderly succession.

He had already given his two eldest sons a share in the government in 815, when he had sent his elder sons Lothair and Pepin to govern Bavaria and Aquitaine respectively, though without the royal titles.

Now, he proceeds to divide the empire among his three sons and his nephew Bernard of Italy: Lothair is proclaimed and crowned co-emperor in Aachen by his father.

He is promised the succession to most of the Frankish dominions (excluding the exceptions below), and will be the overlord of his brothers and cousin.

Bernard, the son of Charles's son Pippin of Italy, is confirmed as King of Italy, a title he had been allowed to inherit from his father by Charles.

Pepin is proclaimed King of Aquitaine, his territory including Gascony, the march around Toulouse, and the counties of Carcassonne, Autun, Avallon and Nevers.

Louis, the youngest son, is proclaimed King of Bavaria and the neighboring marches.

If one of the subordinate kings dies, he is to be succeeded by his sons.

If he dies childless, Lothair will inherit his kingdom.

In the event of Lothair dying without sons, one of Louis the Pious' younger sons will be chosen to replace him by "the people".

Above all, the Empire will not be divided: the Emperor will rule supreme over the subordinate kings, whose obedience to him is mandatory.

With this settlement, Louis tries to combine his sense for the Empire's unity, supported by the clergy, while at the same time providing positions for all of his sons.

Instead of treating his sons equally in status and land, he has elevated his first-born son Lothair above his younger brothers and given him the largest part of the Empire as his share.

The appointment of 'Ali ar-Rida arouses varying reactions—few of them, even among the Shi'ites, wholly favorable—and Iraq, already irritated by al-Ma'mun's transfer of the capital from Baghdad to Merv and by other offenses, rises up in rebellion.

In July 817, after news reaches the city that Ma'mun has chosen an Alid, Ali ibn Musa al-Rida, as his heir-apparent, the city appoints his uncle, Ibrahim, son of the third caliph, al-Mahdi, as Caliph.

A requirement of Tantric Buddhism, that rites be performed in secret but with the congregation present, leads to the development of forehalls in Tantric “kondos,” such as the one built at Koryuji in about 818.