John the Deacon (fl. 500) was a deacon in the Church of Rome during the pontificate of Pope Symmachus (498–514). He is known only from an epistle he wrote to a Senarius, a vir illustris who had asked him to explain aspects of Christian initiatory practice. John's response provides a "rather full description" of the catechumenal process and initiation rites at Rome at the beginning of the 6th century.

John describes his first-hand experience of the liturgical rites of initiation as practiced at Rome, and the theology behind them.^[1] Two specific rites, namely a cross traced on the forehead and a taste of blessed salt, marked the entrance into the catechumenate,^[2] "so the mind which is drenched and weakened by the waves of this world is held steady".^[3]

John also covers prebaptismal exorcisms; the anointing of the ears, nostrils, and breast of the candidate; the use of milk and honey for first communion; ritual nudity and immersion; special white clothing for the newly baptized; and the need for even infants to undergo the process, saying that "Their salvation should come through other people's profession, since their damnation came by another's fault."