One might ask with regard to our duty to influence the nations based on a ruling in the Shulchan Aruch:
One should be careful not to enter into a partnership with a gentile, lest the gentile be required to take an oath, and the Jew will thus violate the prohibition, “You must not cause it to be heard through your mouth.”
From this ruling it appears that the only reason a Jew must prevent a non-Jew from swearing by his idol is to avoid his own prohibition of causing the name of an idol to be mentioned. Yet, according to the above analysis, this would necessarily involve an independent obligation. Indeed, a Jew is obligated to influence (“compel”) the non-Jew not to violate his own prohibition against idolatry.
The difficulty is even greater when we consider the laws of commerce. The Shulchan Aruch rules that “Items that are designated for a particular type of idolatrous worship... may not be sold to those who worship that idol... (due to the prohibition of lifnei iver — ‘placing a stumbling block before the blind,’ i.e., enabling another to sin). If, however, the buyer purchases the items for commercial resale, the sale is permitted.” That is, one may sell to someone who is not himself “a worshipper of that idol,” even though that purchaser will then go on to sell the item to “a worshipper of that idol,” because “we are commanded with respect to lifnei iver, but we are not commanded with respect to lifnei d’lifnei (placing a stumbling block before one who will place a stumbling block).”
Furthermore, some authorities rule that even selling directly to “those who worship that idol” is prohibited only when “they have no other similar item available, or they cannot purchase it elsewhere; but if they are able to purchase it in another place, it is permitted to sell it to them,” because in such a case the prohibition of lifnei iver does not apply.
This is perplexing: if there is an obligation to compel Noachides to accept the Seven Laws, it should certainly follow — at the very least — that a Jew may not perform any action that enables a non-Jew to violate those laws, even in cases where the technical prohibition of lifnei iver does not apply.
[Even though the primary focus of the command given to Moshe was to endeavor that the inhabitants of the world accept the laws, it is obvious and self-evident that one should not act in a way that assists them in violating those very laws — the exact opposite of the “acceptance” the Jew is supposed to achieve!]
