If you believe in angels then you must believe in their evil counterparts. Whether or not we are subject to actual influence by these entities, can be affected by many factors. In 550 or so St. Gregory wrote about the miracles that were performed  and evil influences abolished by St. Benedict weilding the cross with confidence. He and the Benedictines that followed him found that it defeated the forces of evil every time. His followers developed this original idea into a medal so powerful that no demon can stand to be in it's presence when it is worn with confidence. For many centuries this medal existed without anyone understanding what the mysterious symbols stood for. Then in 1647 a manuscript dating to 1415 revealed what had been hidden for so long. Each letter stood for a latin word. The first line on the arms of the cross is Crux sacra sit mihi lux! Nunquam draco sit mihi dux! (May the holy cross be my light! May the dragon never be my guide!). Above the cross is the word pax (peace), a Benedictine motto for centuries. Around the margin of the back of the medal, the letters V R S N S M V - S M Q L I V B are the initial letters, as mentioned above, of a Latin prayer of exorcism against Satan: Vade retro Satana! Nunquam suade mihi vana! Sunt mala quae libas. Ipse venena bibas! (Begone Satan! Never tempt me with your vanities! What you offer me is evil. Drink the poison yourself!) Finally in 1880, the Benedictines standardized the medal to the one we have today that we call the Exorcism Medal of The Cross-Medal of St. Benedict. Worn on a chain, placed on a key chain, or in your car or home, or even in the foundation of a building, it is your best protection from the evil influences that defeat us time and time again. Fight back.