one who stands surety for another in the rite of Christian Baptism. In the modern baptism of an infant or child the godparent or godparents make profession of faith for the person being baptized (the godchild) and assume an obligation to serve as proxies for the parents if the parents either are unable or neglect to provide for the religious training of the child, in fulfillment of baptismal promises. In churches mandating a sponsor only one godparent is required; two (in most churches, of different sex) are permitted. Many Protestant denominations permit but do not require godparents to join the infant's natural parents as sponsors. In the Roman Catholic Church godparents must be of the Catholic faith.

The practice of sponsorship originated not in infant baptism but in the custom that required that an adult pagan who offered himself for the rite should be accompanied by a Christian known to the bishop—a Christian who could vouch for the applicant and undertake his supervision. The Greek word for the person undertaking this function was anadochos, to which the Latin susceptor is equivalent. The word sponsor in this ecclesiastical sense occurred for the first time in Tertullian's (Tertullian) 2nd-century treatise De Baptismo. The sponsors to whom he alluded may have been in many cases the actual parents, and even in the 5th century it was not felt to be inappropriate that they should be so; Augustine (Augustine, Saint) in one passage appears to speak of it as a matter of course that parents should bring their children and answer for them, and the oldest Egyptian ritual bears similar testimony. Elsewhere Augustine contemplated masters bringing the children of slaves, and of course orphans and foundlings were brought by other benevolent persons.

The comparatively early appearance, however, of such names as compatres, commatres, propatres, promatres, patrini, and matrinae seems to prove not only that the sponsorial relationship had come to be regarded as a very close one but also that it was not usually assumed by the natural parents. How very close it was held to be is shown by the emperor Justinian's (Justinian I) prohibition of marriage between godparents and godchildren. On the other hand, the anciently allowable practice of parents becoming sponsors for their own children, though gradually becoming obsolete, seems to have lingered until the 9th century, when it was at last formally prohibited by the Council of Mainz (813). For a long time there was no fixed rule as to the necessary or allowable number of sponsors, and sometimes the number actually assumed was large. By the Council of Trent (Trent, Council of) (1545–63), however, it was decided that one only, or at most two, these not being of the same sex, should be permitted. In the Roman Catholic church the spiritual relationship established between the sponsor and the baptized, and the sponsors and the parents of the baptized, continues to constitute an impediment to marriage.