The Hexagram is a myth based upon an undisclosed Church in Washington Beach. The Hexagram symbol can be seen on this Church. The Hexagram symbol has always been the point of controversial subjects, it's origin is highly disputed. It is likely that Rockstar placed it intentionally to cause such upheaval.
This Hexagram is used in real life as a symbol for churches of the Orthodox faith. Especially in the Balkans, a Hexagram is usually used in combination with the Cross to represent Christianity on churches. For Roman Catholics, the Hexagram has a symbolic meaning and refers to The Star of Creation. The Hexagram, along with the Menorah, is the symbol associated with Judaism, called the Star of David.