"Beloved, believe not every spirit, but try the spirits whether they are of God: because many false prophets are gone out into the world." (1 John 4:1, #KJV)

You can't believe everything that everyone tells you. We are responsible to figure out whether what is being said is spiritual or not. Later on in this passage, we are told that they way to find out if someone is preaching the correct gospel is by simply asking the question: "Is Jesus Christ the Son of God?" Those that admit it are of God and those that attempt to remove His deity are not. 1 John 4 is beyond clear on this matter.