Paul the Deacon (c. 720s – 13 April probably 799), also known as Paulus Diaconus, Warnefred, Barnefridus and Cassinensis, (i.e. "of Monte Cassino"), was a Benedictine monk and historian of the Lombards.

An ancestor named Leupichis entered Italy in the train of Alboin and received lands at or near Forum Julii (Cividale del Friuli). During an invasion the Avars swept off the five sons of this warrior into Pannonia, but one, his namesake, returned to Italy and restored the ruined fortunes of his house. The grandson of the younger Leupichis was Warnefrid, who by his wife Theodelinda became the father of Paul.

Born between 720 and 735 in Friuli in Italy to this possibly noble Lombard family, Paul received an exceptionally good education, probably at the court of the Lombard king Ratchis in Pavia, learning from a teacher named Flavian the rudiments of Greek. It is probable that he was secretary to the Lombard king Desiderius, a successor of Ratchis; it is certain that this king's daughter Adelperga was his pupil. After Adelperga had married Arichis II, duke of Benevento, Paul at her request wrote his continuation of Eutropius.

Paul the Apostle (c. AD 5 – c. AD 67; variously referred to as the "Apostle Paul" or "Saint Paul"), also known as Saul of Tarsus, is perhaps the most influential early Christian missionary. The writings ascribed to him by the church form a considerable portion of the New Testament. The influence on Christian thinking of the epistles ascribed to him has been significant, due in part to his association as a prominent apostle of Christianity during the spreading of the Gospel through early Christian communities across the Roman Empire.

According to the writings in the New Testament, Paul was known as Saul prior to his conversion, and was dedicated to the persecution of the early disciples of Jesus in the area of Jerusalem. While traveling from Jerusalem to Damascus on a mission to "bring them which were there bound unto Jerusalem", the resurrected Jesus appeared to him in a great light. Saul was struck blind, but after three days his sight was restored by Ananias of Damascus, and Paul began to preach that Jesus of Nazareth is the Jewish Messiah and the Son of God.

 Martin Luther (help·info) (10 November 1483 – 18 February 1546) was a German monk, priest, professor of theology and iconic figure of the Protestant Reformation. He strongly disputed the claim that freedom from God's punishment for sin could be purchased with money. He confronted indulgence salesman Johann Tetzel with his Ninety-Five Theses in 1517. His refusal to retract all of his writings at the demand of Pope Leo X in 1520 and the Holy Roman Emperor Charles V at the Diet of Worms in 1521 resulted in his excommunication by the pope and condemnation as an outlaw by the Emperor.

Luther taught that salvation is not earned by good deeds but received only as a free gift of God's grace through faith in Jesus Christ as redeemer from sin. His theology challenged the authority of the Pope of the Roman Catholic Church by teaching that the Bible is the only source of divinely revealed knowledge and opposed sacerdotalism by considering all baptized Christians to be a holy priesthood. Those who identify with Luther's teachings are called Lutherans.