Our Lord warns us of false teachers in Matthew 7:15, "Beware of false prophets, who come to you in sheep’s clothing, but inwardly they are ravenous wolves." They will appear to be godly, but they are not. "For Satan himself transforms himself into an angel of light" (2 Corinthians 11:14). What makes false teachers so dangerous to our souls, is their appearing to be righteous. "For many false prophets have gone out into the world" (1 John 4:1). We have many false teachers today with all of their differing false denominational doctrines. We also read in Acts 20:30, "Also from among yourselves men will rise up, speaking perverse things, to draw away the disciples after themselves." False teachers are becoming more prevalent within the churches of Christ with the apostasy that is now occurring. 2 Peter 2:1 says, "there will be false prophets among you, who will secretly bring in destructive heresies." Notice they do it secretly and people are unaware of what is happening. They are destructive because of all of the souls that will be lost.
How do false teachers spread their false doctrine? "By smooth words and flattering speech deceive the hearts of the simple" (Romans 16:18). Also "By covetousness they will exploit you with deceptive words" (2 Peter 2:3). What they say may sound good, and they will get many people to follow after them. We are not to be "tossed to and fro and carried about with every wind of doctrine, by the trickery of men in the cunning craftiness of deceitful plotting" (Ephesians 4:14).
We are warned, "Do not be carried about with various and strange doctrines" (Hebrews 13:9). Why? Because we are to "Let no one cheat you of your reward" (Colossians 2:18). We can be cheated and lose our souls forever in eternal punishment if we follow any of the many false doctrines that are being promoted today.
How should we treat those who are promoting their false teaching? 2 John 10-11 says, "If anyone comes to you and does not bring this doctrine, do not receive him into your house nor bid him God speed; for he that bids him God speed is partaker of his evil deeds." We must never give anyone encouragement in their false teaching. If we do, we also become guilty with them. So we must beware of false teachers for they are very dangerous to our souls. We must "search the scriptures daily to find out whether these things were so" (Acts 17:11). Because it is "the Holy Scriptures, which are able to make you wise for salvation" (2 Timothy 3:15).