During the Babylonian exile the Sabbath and circumcision became the characteristic symbols of Judaism. This seems to be the underlying idea of Isa. lvi. 4: “The eunuchs that keep my Sabbath” still “hold fast by my covenant,” though not having “the sign of the covenant” (Gen. xvii. 11, Hebr.) upon their flesh. Contact with Grecian life, especially at the games of the arena, made this distinction obnoxious to the Hellenists, or antinationalists; and the consequence was their attempt to appear like the Greeks by epispasm (“making themselves foreskins”; I Macc. i. 15; Josephus, “Ant.” xii. 5, § 1; Assumptio Mosis, viii.; I Cor. vii. 18; , Tosef., Shab. xv. 9; Yeb. 72a, b; Yer. Peah i. 16b; Yeb. viii. 9a). All the more did the law-observing Jews defy the edict of Antiochus Epiphanes prohibiting circumcision (I Macc. i. 48, 60; ii. 46); and the Jewish women showed their loyalty to the Law, even at the risk of their lives, by themselves circumcising their sons.
In order to prevent the obliteration of the “seal of the covenant” on the flesh, as circumcision was henceforth called, the Rabbis, probably after the war of Bar Kokba (see Yeb. l.c.; Gen. R. xlvi.), instituted the “peri’ah” (the laying bare of the glans), without which circumcision was declared to be of no value (Shab. xxx. 6). […]
The issue between the Zealot and Liberal parties regarding the circumcision of proselytes remained an open one in tannaitic times; R. Joshua asserting that the bath, or baptismal rite, rendered a person a full proselyte without circumcision, as Israel, when receiving the Law, required no initiation other than the purificative bath; while R. Eliezer makes circumcision a condition for the admission ofa proselyte, and declares the baptismal rite to be of no consequence (Yeb. 46a). […]
Unlike Christian baptism, circumcision, however important it may be, is not a sacrament which gives the Jew his religious character as a Jew. An uncircumcised Jew is a full Jew by birth (Ḥul. 4b; 'Ab. Zarah 27a; Shulḥan 'Aruk, Yoreh De’ah, 264, 1). […]
After having for centuries been practised as a distinctively Jewish rite, circumcision appeared to many enlightened Jews of modern times to be no longer in keeping with the dictates of a religious truth intended for humanity at large; and its abolition was advocated, and made the shibboleth of the “Friends of Reform” (“Reformfreunde”) in Frankfort-on-the-Main in 1843. […] A bitter controversy raged in the Jewish congregations and press. Samuel Holdheim took sides with the Radical Reformers; David Einhorn, with a number of other rabbis, opposed the merely negative Standpoint of the Frankfurt Reform-Verein, but emphatically indorsed the view that he who disregards the law of circumcision, whatever the motive may be, is nevertheless a Jew, circumcision having no sacramental character. […]
In 1847 Einhorn, as chief rabbi of Mecklenburg, became involved in a controversy with Franz Delitzsch of Rostock, who denounced him for acting contrary to Jewish law in naming and consecrating an uncircumcised child in the synagogue. Einhorn, in an “opinion,” published a second time in his “Sinai,” 1857, pp. 736 et seq., declared, with references to ancient and modern rabbinical authorities, that a child of Jewish parents was a Jew even if uncircumcised, and retained all the privileges, as well as all the obligations, of a Jew.