Josephus on the repentance of John the Baptist
Josephus makes four points about message of John the Baptist.
John exhorted Jews to begin to live righteous lives towards one another and piety towards God. In other words, John preached the necessity of what Jews referred to as repentance, teshuva, the turning from sin to obedience to the Law.
John required that those who responded to his message to undergo a baptism. He understands it first as a purification of the body, playing the same role as the traditional mikvah. Josephus strongly denies that John claimed any power to forgive sins. Josephus says that John’s baptism was not for the remission of sins, but was for the purification of the body due to the fact that the soul was already purified by the people’s return to righteousness prior to coming for John’s baptism. The Gospel writers appear to indicate that John’s baptism of repentance was for the remission of sins. Luke and Mark both report that John came “preaching a baptism of repentance for the forgiveness of sins.” Matthew and Mark state that people were confessing their sins to John.
John insisted that the cleansing of the "soul" resulted from the repentance and not from baptism. What he means by the "cleansing of the soul" is the forgiveness of sins, which he insisted was conditional upon repentance and not baptism.
Josephus's interpretation of the baptism that John required Jews to undergo was that it was a "consecration of the body," seeing that the "soul" was already cleansed by means of repentance. Probably, by the "consecration of the body," Josephus is referring to ritual lustration. If so, John offered the possibility of both forgiveness and ritual purity.