Baptism of blood
In Christian theology, baptism of blood or baptism by blood, also called martyred baptism, is a doctrine which holds that a Christian is able to attain through martyrdom the grace of justification normally attained through baptism by water, without needing to receive baptism by water.
Patristic period
Based on passages from the New Testament, many early Christian authors distinguished between water baptism and the second baptism, which was sometimes called blood baptism, but usually called martyrium. In water baptism, man was purified on a conscious level. By the second baptism, the Christian was also delivered from his own “demons” on an unconscious level. Then the resurrection of the soul takes place: the 'old man' is changed into the 'new man' who receives the promise of eternal life in paradise after death. To endure the second baptism, it was common for Christians to submit to horrific forms of torture in which they could lose their lives. They could also survive. It did not matter, because Christians were concerned with the life of the soul and not the life of the body. The soul received the guarantee of eternal life in paradise. From this perspective, the deaths of Christian martyrs were probably not the result of the persecutions of Roman emperors.Cyprian of Carthage in a letter of 256 regarding the question of whether a catechumen seized and killed due to his belief in Jesus Christ "would lose the hope of salvation and the reward of confession, because he had not previously been born again of water", answers that "they certainly are not deprived of the sacrament of baptism who are baptized with the most glorious and greatest baptism of blood".
Cyril of Jerusalem states in his Catechetical Lectures delivered in Lent of 348 that "if any man receive not Baptism, he hath not salvation; except only Martyrs, who even without the water receive the kingdom".
Denominations' opinions
Overview
The baptism of blood doctrine is held by the Catholic Church, the Oriental Orthodox Churches, the Eastern Orthodox Church, and the American Association of Lutheran Churches.Lutheranism
Those who die as Christian martyrs in a persecution of Christians are judged by Lutherans as having acquired the benefits of baptism without actually undergoing the ritual.The Augsburg Confession of Lutheranism affirms that "Baptism is normally necessary for salvation". Citing the teaching of the early Church Fathers, Lutherans acknowledge a baptism of blood in "the circumstances of persecution".