Dear Rabbi, I have a fine wine made from grapes only, but the bottle does not state it to be kosher. Why is it not considered kosher, i.e. what non-kosher ingredient do we fear it might contain? Thank you.
There is nothing intrinsically non-Kosher about the ingredients of a wine that has no additives. What makes wine non-Kosher? Any wine that was not supervised through the entire process of making the wine is not kosher. The main concern is that a non-Jew may touch the wine before it is boiled and this would give it a status of "Stam Yayin". Even though the wine wasn't used for pagan worship (which is called "Yayin Nesech"), which would make it forbidden according to Torah law, it still becomes non-kosher according to Rabbinical law as a deterrent to intermarriage for one reason. The ruling appears in the Code of Jewish Law Yoreh Deah, 123:1.
