The X is a multi-faceted symbol.  It is not only a combo of the two chevrons (chalice/blade), but also represents the LVX “light” concept, reminds us of the damaru drum of India (Shiva-Shakti sacred sex), is the gesture ancient christians made with their arms across their chest while approaching the altar (God) for communion (Orthodox still do this), and was used by medieval painters of Mary Magdalene to show her connection to Christianity’s most sacred marriage of all.

Mary Magdalene by Jan Van Scorel, 1529.  Thanks to Olga’s Gallery at http://www.abcgallery.com/S/scorel/scorel2.html. This painting holds lots of secrets! Note the vivid colors — Mary Magdalene’s mysterious smile really lights up with that secret spark in her eye.  The X’s are made of pearls, the pearl being another symbol of the sacred feminine and other mysteries.  AND best of all, it looks like a secret message in Hebrew letters across the neckline of her dress!

The X in Grail Heresy Watermarks

The X in mainstream Christianity’s view is found at Christian Symbols.