Halakhah zu Dewarim 7:3

The most obvious source of this ban is Deuteronomy 7:3: "Neither shalt thou enter into marriage with them; thy daughter thou shalt not give unto his son, nor his daughter shalt thou take unto thy son. For he will turn away thy son from following Me, that they may serve other gods." However, the source which appears to be the most evident is not necessarily the most correct. The exegetical problem attendant upon this apparently explicit reference is whether the prohibition encompasses only the "Seven Nations" who at that time inhabited Erez Yisra'el, or whether it includes all gentile nations as well. This verse is immediately preceded by an introductory sentence in which the Torah states, "When the Lord thy God shall bring thee into the land whither thou goest to possess it, and shall cast out many nations before thee … seven nations greater and mightier than thou." The prohibition occurs within a specific historic context, viz., entry into the promised land and conquest of the seven indigenous nations who inhabited Erez Yisra'el. These seven nations are specifically enumerated in this verse. It is in this context that the Torah admonishes, "Neither shalt thou enter into marriage with them."

If a Jew engages in sexual relations with a female idolater, derech ishut (that is, for the purpose of marriage), or a Jewess engages in sexual relations with a male idolater, that Jew or Jewess is given lashes on a Biblical level. As it is written (Deuteronomy 7:3): "You shall not marry them." (There are those who disagree with this ruling). However, if he engages in sexual relations derech zenut (that is, for licentiousness), casually, he is culpable only on a Rabbinic level for idolatry and for engaging in relations with a prostitute and he is given makat mardut (that is, lashes on a Rabbinic level). And, if he sets her aside for licentious activity, he is culpable on a Rabbinic level for having sexual relations with a nida (that is, menstruant), having sexual relations with a shifcha, (that is, slavewoman), idolatry, and having sexual relations with a prostitute. And, if he is a Kohen (that is, a priest), even if he engages in sexual relations casually, he receives lashes on a Biblical level, as it is written (Leviticus 21:7) ["(A kohen) may not marry a prostitute..."]

Another authority, Avnei Milu'im, Even ha-Ezer 16:1, adduces yet another proof in establishing a biblical commandment prohibiting a Jewess from cohabiting with a non-Jew. According to Avnei Milu'im, the primary reference of the verse "For he will turn away thy son from following Me" (Deuteronomy 7:3) is to a Jewess who consorts with a non-Jew and applies only secondarily to a Jew who cohabits with a gentile woman. In the latter case, argues this authority, a child born of the liaison is a gentile and cannot properly be spoken of as "thy son," since Jewish law recognizes no relationship between a Jewish father and his non-Jewish progeny. However, since the child of a Jewish mother is a Jew even if the father is a non-Jew, a filial relationship does exist in Jewish law between the child and the mother. Accordingly, concludes Avnei Milu'im, in speaking of intermarriage as being forbidden "For he will turn away thy son from following Me" the verse must be addressed primarily to Jewish women. Hence, this verse serves to establish the existence of a biblical prohibition against cohabitation between a Jewess and a gentile.