What we have to realize is that, for the ancient exegetes, sexual relations with a pagan woman, outside marriage or within it, were associated with the risk of idolatry. The Mishnaic threat, ‘He who has sexual intercourse with an Aramean woman, zealots (v.l. the Zealots) shall fall upon him’ (m. Sanh. 9:6) is linked in interpretative tradition with Lev. 18:21. The Aramean woman seems to be the prototype of the seductress and the whore: ‘Do not sit on the bed of an Aramean woman’ – exhorts the Talmud (b. Ber. 8b; b. Pes. 112b). And the mention of zealot intervention is a reminder of the biblical story of Israelite misbehaviour recorded in Num. 25, the whoring after the Moabite women, and of the outraged Pinhas’s ‘zealous’ act when he slew with a single blow the Jewish notable Zimri and his paramour Cozbi caught in flagrante delictu (Num. 25:7-9, 14-15). It should also be recalled that according to the midrashic version of Numbers 25, the Moabite women used sex as a means to promote idolatry. They inebriated their Israelite lovers with the strong Ammonite wine and, when they were aroused, each took out of her bosom a little statue of Baal Peor and asked the man to worship it. If he protested that idolatry was not the purpose of his visit, she explained that, to worship Baal Peor, all he needed to do was to undress. This equivocal act of worship – which, in the circumstances, did not seem inordinately out of place – was however not the end to it. ‘Renounce the Torah of Moses – she said – and then I will give myself to you.’
Gaza Vermes, “Leviticus 18:21 in Ancient Jewish Bible Exegesis” in Studies in Aggadah, Targum and Jewish Liturgy in Memory of Joseph Heinemann, ed. Jakob J. Petuchowski & Ezra Fleischer (Jerusalem: The Magnes Press, The Hebrew University; Cincinnati: Hebrew Union College Press, 1981), 116.