We are warned about what we call antichrist. This is someone who may pretend to be Christ. It can also be someone, or a religious organization. Now mind you it is important to know who Christ is before you can detect a person or a religious group who are antichrist. John says they went out from us but they have no part with us, or they would have stayed with us. Jude speaks of them as having crept in. Even now they want to corrupt unsuspecting new Christians, or those who haven’t’ grown in Christ. Be careful not to be led away with the error of the wicked.
Verse 20 says we have an unction with the” Holy One” and know all things. John says, “I wrote to you to know the truth, and no lie is of the truth.” The liar is someone who denies the Father and the Son. John calls such a person antichrist. Many can talk about God, but without Christ we have no God.