A basic definition of the term “martyr” is provided by Origen: “One who of his own free choice chooses to die for the sake of religion.” The Greek word (martys) means simply “witness” in the legal sense, and it carries this neutral connotation in several NT passages (e.g., Mark 14:56,59,63; Luke 22:71). The ground, however, is already prepared in the NT for the later development of the term, when it becomes the equivalent of a blood witness, i.e., one who dies for his faith and “prefers to die rather than deny his religion and live” (Origen). Stephen (cf. Acts 22:20) is appealed to in the later church as the “perfect martyr” as well as the protomartyr. An otherwise unknown figure, Antipas (Rev. 2:13) is mentioned as both a martyr and a Christian who was killed for his faith. In the Apocalypse the term receives its full technical sense (cf. 6:9; 17:6; 20:4).
The background of the idea, if not the precise term itself, lies in Jewish history, especially in the prophets' fidelity to their mission and consequent suffering. In particular, at the time of the Maccabean struggle against the Syrians, the main traits of Jewish martyrdom which later were to influence the Christian martyrs were fixed. These are seen in such features as the expiatory element in human suffering and an apocalyptic dimension that provided the necessary fanaticism to overcome first the Syrian dictator and then the Roman power. The belief in resurrection, clearly articulated in the Maccabean age, obviously was a needed conviction to sustain the Christian heroes and heroines.
In retrospect, both Paul's and Peter's deaths are hailed as acts of martyrdom. With Ignatius of Antioch (c.115) the thought of the martyr's conscious imitation of his Lord's passion appears (Phil. 2:7; Rom. 6:3), and this formed a powerful motif in the later martyrologies.
One early martyrdom became the model for all subsequent resistance unto death. Polycarp* of Smyrna died after interrogation in the amphitheater; and his hagiographer has graphically recorded his last days in a way which became standard for later Acta. The veneration of the martyrs' bones was a practice which began with Polycarp's remains, and an annual event was observed as a “celebrating of the birthday of his martyrdom.” This is the origin of the idea of martyrology by which is meant the commemoration of the martyrs' sacrifice. Later, intercessory powers were attributed to the martyr.
The fullest description of early Christian martyrs is that of those who died in Lyons and Vienne in Gaul. The later persecutions under Decius (whose edict in 250 initiated the first universal and systematic persecution of the church) and Diocletian (303) produced their crop of martyrs both in the strict sense of those who chose to die rather than recant and those who were confessors and were tortured for their faith.
The standard work with its full bibliography is W.H.C. Frend, Martyrdom and Persecution in the Early Church (1965).