People have a responsibility to check the source of what they share on social media to ensure it is not "fake news" designed to further prejudices or increase fear, Pope Francis said. Fake news grabs people's attention "by appealing to stereotypes and common social prejudices, and exploiting instantaneous emotions like anxiety, contempt, anger and frustration," Pope Francis wrote in his message for World Communications Day 2018. The message is a reflection on the theme, "'The truth will set you free.' Fake news and journalism for peace." World Communications Day will be celebrated May 13 at the Vatican and in most dioceses. The papal message was released at the Vatican on January 24, the feast of St Francis de Sales, patron saint of journalists. Fake news is so effective, he said, because it mimics real news but uses "non-existent or distorted data" to deceive and manipulate. The first to employ the fake-news tactic was the serpent in the Garden of Eden who convinced Eve she would not die by eating the fruit of the forbidden tree, he said. The Bible story shows that "there is no such thing as harmless disinformation; on the contrary, trusting in falsehood can have dire consequences."