I just read an excellent book, The Historian by Elizabeth Kostova. The eponymous historians in the book are searching for Dracula. The characters are not particularly religious, but find that wearing crosses can help protect them from the undead.
And, that got me thinking about the powerful protection of a crucifix.
Now, I don't believe in vampires - or the undead - or anything like that. But I do believe that evil exists. You don't have to go much further than the front page of the newspaper to see that evil is real and is all around us.
Will wearing a crucifix protect us from all evil? Of course not. It's not a good luck charm. But the way I see it, it works this way. God protects us from evil. We ask it of him whenever he pray the Our Father.
The evil we need most to be protected from is the evil that can take root within us. But, that evil cannot take root if we are filled with God's love. Two things cannot exist in the same place at the same time. If we are filled with love, we can not be filled with hate.
A crucifix protects us from evil - not because vampires are afraid of it (though, if vampires were real, they probably would be afraid of it) but because it is an outward sign of the love we have within us.
Love protects us from evil. And God is Love.