Martin Luther (1483-1546) was a German monk, theologian, university professor and church reformer whose ideas inspired the Protestant Reformation and changed the course of Western civilization. Luther's theology challenged the authority of the papacy by holding that the Bible is the only infallible source of religious authority and that all baptized Christians under Jesus are a spiritual priesthood. According to Luther, salvation was a free gift of God, received only by true repentance and faith in Jesus as the Messiah, a faith given by God and unmediated by the church. Luther's confrontation with Charles V at the Diet of Worms over freedom of conscience in 1521 and his refusal to submit to the authority of the Emperor resulted in his being declared an outlaw of the state as he had been excommunicated from the Roman Catholic Church. Because of the perceived unity of the medieval Church with the secular rulers of western Europe, the widespread acceptance of Luther's doctrines and popular vindication of his thinking on individual liberties were both phenomenal and unprecedented. His translation of the Bible into the vernacular, making it more accessible to ordinary people, had a tremendous political impact on the church and on German culture. It furthered the development of a standard version of the German language, added several principles to the art of translation, and influenced the translation of the English King James Bible. His hymns inspired the development of congregational singing within Christianity. His marriage to Katharina von Bora set a model for the practice of clerical marriage within Protestantism. Much scholarly debate has concentrated on Luther's writings about the Jews. His statements that Jews' homes should be destroyed, their synagogues burned, money confiscated and liberty curtailed were revived and used in propaganda by the Nazis in 1933–45. As a result of this and his revolutionary theological views, his legacy remains controversial.

Saint Peter also known as Peter the Apostle, Simon Peter, Simeon, or Simon was one of the Twelve Apostles of Jesus Christ and one of the first leaders of the early Christian Church. He appears repeatedly and prominently in all four New Testament gospels as well as the Acts of the Apostles. According to Christian tradition, Peter was crucified in Rome under Emperor Nero. The ancient Christian churches all venerate Peter as a major saint and as the founder of the Church of Antioch and the Church of Rome, but they differ in their attitudes regarding the authority of his successors. According to Catholic teaching, Jesus promised Peter a special position in the Church. In the New Testament, the name "Simon Peter" is found 19 times. He is the brother of Saint Andrew, and both were fishermen. The Gospel of Mark in particular was traditionally thought to show the influence of Peter's preaching and eyewitness memories. He is also mentioned, under either the name Peter or Cephas, in Paul's First Letter to the Corinthians and the Epistle to the Galatians. The New Testament also includes two general epistles, First Peter and Second Peter, that are traditionally attributed to him, but modern scholarship generally rejects the Petrine authorship of both.[8] Nevertheless, Evangelicals and Catholics have always affirmed Peter's authorship, and recently, a growing number of scholars have revived the claim of Petrine authorship of these epistles. Catholic and Orthodox tradition accredits him as the first bishop of Rome‍—‌or pope‍—‌and also as the first bishop of Antioch. Based on contemporary historical data, his papacy is estimated to have spanned from AD 30 to his death, which would make him the longest-reigning pope, at anywhere from 34 to 38 years; however, this has never been verified. Saint Irenaeus explains the Apostle Peter, his See, and his successors in book III of Adversus Haereses (Against Heresies). In the book, Irenaeus wrote that Peter and Paul founded and organized the Church in Rome. Sources suggest that at first, the terms episcopos and presbyteros were used interchangeably, with the consensus among scholars being that by the turn of the 1st and 2nd centuries, local congregations were led by bishops and presbyters, whose duties of office overlapped or were indistinguishable from one another. Protestant and secular historians generally agree that there was probably "no single 'monarchical' bishop in Rome before the middle of the 2nd century...and likely later." Outside of the New Testament, several apocryphal books were later attributed to him, in particular the Acts of Peter, Gospel of Peter, Preaching of Peter, Apocalypse of Peter, and Judgment of Peter, although scholars believe these works to be pseudepigrapha.