circumcision but upon the heart. One[i.e., a candidate for proselytizing] who does not believe sincerely is not converted to Judaism by his circumcision. But one who believes sincerely, is a full Jew even if he is not circumcised."
Some participants in the older Conference debate quote a responsum of the famous rabbi of Constantinople in the fifteenth century, Elijah Mizrachi , in his Mayyim Amuqgim#27(the correct reference in the Berlin edition should be#34), in which there is discussion of a Gentile woman and her child who are to be converted, in which he says, with regard to the child, the law mide-oraita is that the acceptance of the Torah is sufficient even without bathing or circumcision.(However, he proceeds to say that for adults both rites are required. Still he does indicate that according to Torah-law(mide-oraita) the rites are not indispensable.) There is an analogous statement in the Kol Sohol (Behinat Ha-qabbalah) by Leon of Modena . On page 59, where he follows the order of the Shulhan Arukh, he speaks about proselytes. He says we ought to give the proselyte the usual explanatory warning and ascertain his sincerity. Then he adds:"We should tell him of the worth of circumcision and its reward. If, then, he wishes to be circumcised, well and good; if not, let him take the ritual bath, and that is sufficient to make him a full Jew in every sense. But when his children are born, he must circumcise them." It is clear, Modena continues, that as for the proselyte himself, the only Biblical drawback to his not being circumcised is that he cannot participate in the paschal offering, but otherwise the Torah makes no mention of circumcision being necessary for a proselyte. (Evidently those who participated in the Conference debate got their chief arguments here. But it is clear that Modena does not give the law as it is, but as he believes it ought to be.)