I agree with this post completley. I also wanted to add that the sign of the cross is a prayer in itself. It is the first prayer I teach my children. You know how it has become popular to teach infants sign language because they can communicate by action and comprehend before they can effectivly use speech? I think it is so cool that God gives us, his children, so many ways to praise him.
I have never seen this prayer used to ward off evil, but before a difficult situation I have done this prayer to reconnect myself with my baptismal promise to Christ. I kind of say to God, “I know we are in this together…Lets go!” Perhaps the people the original poster saw making the sign of the cross were not ‘warding off evil spirits’, but it was just interpreted that way?
Nevermind…I just reread the original post and I agree with the other post that said that movies often misuse the sign of the cross. I missed the ‘in movies’ reference in the op.