False prophets are often easy to spot: they predict that something will happen, and their prediction fails to eventuate. False teachers are more difficult to detect, because what they say often seems plausible, and is often difficult to disprove. False teaching has been and will always be one of the pitfalls of the Christian church. In the second chapter of his second letter, Peter has this to say about false teachers:
There were false prophets amongst the people, just as there will be false teachers amongst you, secretly introducing destructive opinions, denying even the Master who bought them, bringing on themselves swift destruction. A lot of people will follow their degeneracy, and as a result, the way of the truth will be abused. They will greedily exploit you with misleading words. Their condemnation from long ago will wait no longer, and their destruction will sleep no more.
Like get-rich-quick investment schemes that are too good to be true, leading on to inevitable financial ruin, false teaching about Jesus and the Christian faith often offers short-term allure but carries with it long-term pain. False teachers might tell you that it is OK to hate your enemy, or to take what does not belong to you, or to give in to greed and selfish desires, but there is a price to be paid for the harm caused by those sins.