|Holy Roman Emperor entered into an agreement with Pope Calistus II|
A concordat is a formal agreement between the pope acting in his spiritual function and a state. It is a legal contract between church and state, recognized as a treaty under international law.
The antithesis between temporal and spiritual authority was particularly pronounced in the medieval quarrels leading to the practice of agreeing to concordats such as the Concordat of Worms. A similar compromise, the Concordat of London, in 1107 had resolved the investiture conflict between the pope and the king of England, providing the basis for the Concordat of Worms.
On September 23, 1122, Pope Calixtus II (d. 1124) and Holy Roman Emperor Henry V (1086–1125) agreed under the Concordat of Worms, the Pactum Calixtinum, to end their battle over investiture, the power to appoint to church offices.
The struggle over control over church offices had begun during the time of Henry IV (1050–1106) and Pope Gregory VII (1020–85.) Before the 10th century investiture of church leaders was a church prerogative in practice, but it was often done by kings.
It gave rise to the practice of simony, or the sale of church offices; this was a sin according to the church, but a profitable practice for monarchs. It also created a clergy that was more loyal to the king than to the pope.
The emperor had the power to appoint the pope, who had the power to appoint the emperor. Gregorian reformers in the church wanted to end the practice of simony, but they needed to break the appointment tie, which they did in the reign of young Henry IV in 1059.
The reformers created the college of cardinals to replace the emperor as selector of future popes. In 1075 Gregory VII decreed that the church alone had the power over appointments. Henry IV removed the pope, and Gregory retaliated by excommunicating Henry. The struggle between emperor and pope gave Henry’s nobles the opportunity they sought; they rose against him.
In 1077 Henry apologized, wearing a hair shirt to Canossa and receiving papal forgiveness. After crushing his rebellious nobles, he turned to replacing the pope with a more pliable one. The investiture controversy continued into the next generation of pope and emperor.
Henry V agreed to bar bribery and allow free election of bishops and abbots, renouncing his right to invest them with the symbols of their office. The pope in return allowed Henry to attend elections in Germany and to invest the elected with their lay rights and obligations before they were consecrated. Generally, the clergy chose bishops and abbots, but the emperor decided contested elections.
The emperor invested the elected person with regalia, powers, privileges, and lands pertaining to his role as vassal. After he paid homage to his emperor, he would be invested with the spiritualia, ecclesiastical powers and lands, as symbolized by the ring and crosier, by his ecclesiastical superior.
This compromise provided the basis for relations between popes and Holy Roman Emperors thereafter. The concordat came about as a result of the efforts of Lamberto Scannabecchi (later Pope Honorius II) and the Diet of Wurzburg (1121). Confirmation of the concordat came at the First Lateran Council in 1123.
Later concordats in France included the Concordat of 1516, which gave the king the right to nominate bishops, abbots, and priors, with the pope reserving the rights to confirm and appoint in special circumstances. After the Estates General of Orléans revoked the right in 1561, conflict continued until the French Revolution.