A pentagram might have some associations with forms of devil worship, but that doesn't mean it's always or even usually the case. I've been a Masonic hall where there was a pentagram on the wall - a five-pointed star containing icons representing the six areas of knowledge and learning. There couldn't be anything less evil.

:Edit:
Anyone else seen Fritz Lang's Metropolis? Lots of pentagrams in that film, both regular and inverted.