My understanding is that wine or grape juice is s'tam yenam and forbidden if handled by non-Jews without having been cooked. (See, e.g., an explanation on chabad.org.) The practical result of this, ...
As a non-Jew, undergoing the conversion process, I am very careful regarding the Torah, rabbinic, and cultural laws. However, some times it seems to me that some laws are not compatible for converts. ...
Why are some wines kosher and some not?