The Star of David is easily the strongest and most recognizable symbol of Judaism and Jewish identity. The figure was first emblazoned on King David's battle shield (hence its original name, Magen David, which means David's shield), just to let any enemies of Israel who got close enough to see it know exactly which god he was about to send them to.
"H to the izz-O, V to the izz-A!"
The shield of a divinely backed warrior-king is a pretty sweet logo. Beats the hell out of the Starbucks mermaid, anyway. Too bad the Star of David has absolutely nothing to do with that. The six-pointed star we think of as the ultimate symbol of Judaism is actually just some random shape. It looks neat, so it keeps popping up in various cultures and contexts. The Jewish used it in their ancient synagogues, but it was strictly for decorative purposes. You could see it right there along with other symbols, such as five-pointed stars, flowers, and even swastikas. Weirdest bowl of Lucky Charms we've ever heard of.