That star is the Star of David. It is a symbol of the Jewish faith. Jewish people do not believe the Savior has come yet. Therefore, they only recognize the old testament and not Jesus or the Gospels (new testament).
Anyway, I'd guess that was wine or some sort of a "kosher" drink. Kosher is a way in which something is prepared acceptable to God in the Jewish tradition. Orthodox Jewish do not mix dairy and meat products. I believe the Star on the bottle means the maker is Jewish OR it is telling the consumer the contents have been prepared following the kosher rules.
If I remember blatz was beer. During prohibition a lot of beer makers started producing soft drinks to stay in business. I believe this is what you bottle is. More than likely it is a beer bottle that was used for soda until prohibition was revoked. IM not sure about it being kosher I believe they just used the star on their bottle as part of the design.
Brian