The letter from the writer known as "Jude" is a short, 1 chapter, power packed letter addressing false teachers. False teaching has been around since teaching began. It's simply taking something taught and twisting it then passing the twisted version on to anyone who is willing to listen. False teachers are not necessarily those with opposing views on non-essential doctrines, rather those who are actively teaching things in opposition to sound biblical teaching. Many people have fallen victim to teachers who have not imparted the truth of God to them resulting in a stifled or non-existent relationship with Jesus and Jude is going to expose such teachers.