RRE 11 (2025), 124–147 DO 10.1628/rre-2025-0010 ISSN 2199-4463 © 2025 Yair Furstenberg Yair Furstenberg Christian Reshaping of Jewish Laws of Conversion Abstract Christian baptismal rites evolved from Jewish purification practices. At the same time, during the following centuries the rabbis appropriated major features of Chris- tian baptism, thereby reshaping Jewish conversion. Rabbinic sources testify to the growing role of immersion in water in the conversion procedure. Through the com- parison of the two detailed versions of the rabbinic protocol of conversion, dated to the fourth and fifth centuries and incorporated in the Babylonian Talmud and in tractate Gerim, this paper reconstructs the history of this rabbinised rite. It is argued that the earlier version is to be understood as a ritual response to current forms of Christian baptism, which include two unique elements: a baptiser and a declaration over the water. Against the background of Christian invocation of the credo over the water, the presumably bizarre listing of commandments while still in the water is a rabbinic attempt to encapsulate the essence of the Jewish alternative. Keywords: Baptism, Purification, Rabbinic literature, Talmud, Parting of the ways 1 Introduction Baptism into Christianity evolved from Jewish purification rites of the Sec- ond Temple period. 1 At the same time, the development of Jewish and Chris- tian practices of baptism and immersion in water during the later centuries have been generally considered as clearly distinct phenomena with separate histories. 2 In truth, however, ritual practices and conceptions continued 1 See, for example, Gavin 1969, 26–58; Yarboro Collins 1996; Ferguson 2009. Concern- ing specifically the Baptism of John see Flusser 1988, 50–53; Taylor 1997. For a different approach see Nir 2019. 2 Christian authors have underlined the qualitative difference between the power of Chris- tian baptism and the obsolete Jewish purifications. For example, the Didascalia Apostolo- rum, ch. 26 (Vööbus 1979, 2:238–248) demands of those who converted from the Jewish people to forsake former purifications belonging to the temporary ‘second legislation’, since these practices are not only obsolete, but they deprive these people of the power of the Holy Spirit. Clement of Alexandria claims: ‘But the providence of God as revealed by the Lord does not order now, as it did in ancient times, that aſter sexual intercourse a