Take a moment to think about what information sources you have access to. On a very basic level, you gather information from people or media created by people. Now, if we stop to think about where that media is coming from it’s usually from a group of people focused on a particular belief or a person who is regurgitating their interpretation of that belief. Beliefs that underlie information may (or may not) be transparent; try cross-referencing news sources sometime to see what I’m talking about.
Most people are shaped by the world around them, and there is no greater influence than what information they absorb. If someone only gets their insight into society from a select group of sources that has, at their core, the same set of beliefs, then really that person is only getting one view of the world. Great examples of this concept can often be found by researching the origin of superstitions, holidays, and modern myths: Did you know that frightening gargoyles were once created on the sides of buildings to scare away evil spirits and protect people from harm?