Is Non-Jewish Wine Unkosher? [An Examination of the Rationale Behind Setam Yenam]

The so-called Rabbinic Authority (to which certain Exclusionist Messianic organizations defer) says that wine produced by non-Jews is not kosher:

 "The biblical prohibition of wine used for idolatrous purposes (yayin nesech) was extended in the second century to all wines produced or handled by non-Jews (setam yenam).  The added restriction was based on the assumption that it is the intent of a heathen to put the wine to pagan uses (Avodah Zarah 29b).  The prohibition was also motivated by a rabbinic policy of preventing convivial interfaith gatherings and social intimacy which may lead to intermarriage (Avodah Zarah 36b)," (pg. 96 of The Biblical and HIstorical Background of Jewish Customs and Ceremonies by Abraham Bloch)

So you see that the underlying rationale is that Jews should be prohibited from having social contact with Gentiles (hmm...sounds a little like the story of Peter and Cornelius).  Here's Abraham Chill on the subject:

"THE PROHIBITION OF SOCIAL CONTACT WITH PAGANS 

'Take heed to yourself, that you do not make a covenant with the inhabitants of the land' (Exodus 34:12) 

1.  The scriptural passage above and Deuteronomy 32:38 ('Who did eat the fat of their sacrifices and drank the wine of their drink offering?') teaches us that Jews were forbidden to eat the food or drink the wine that were brought to pagan temples as offerings to the idols of the heathen world. 

2.  Blblical law forbids the drinking of yayin neskh (wine that was used for idol worship) or its use for any other purpose from which Jews might benefit.  Setam yeinam is the ordinary Gentile wine, even when it was not known that it was used for non-Jewish worship.  Under the rabbinic law this wine is subject to the prohibition of yayin nesekh.  Even wine that was prepared by a Jew but had been touched or handled by a non-Jew was forbidden. 

3.  The purpose of these prohibitions was to avoid social contacts that might lead to intermarriage between Jews and pagans.
4.  All who violated these laws were subject to the penalty of lashes,"  (pg. 134 of The Mitzvot by Abraham Chill).