Just a few thing's 1) the inverted cross is nothing to do with the Satanism. It is infact a symbol of faith, a monk wanted to be crucified but didn't feel worthy of being crucified the same as jesus so he was crucified inverted.
2) the correct name for "the devil" is Luciffer Morning Star he doesn't corrupt sould he only punishes those who were evil on arth.
3) Most of what you hear about diabolism was made up by the chirch/the spanish inquisition and Hammer House of Horrors movies.
4) in Austria they believe the devil is an anoying little creature who plays trick and they laugh at him.
5) the sign is nothing to do with evil it is an old italian myth used to avoid the evil eye/ someone giving you an agressive look.