This is a vital skill for a child of God to develop. Most of us have grown up in a counterfeit church. Notice that the counterfeit church does not teach you this skill, because it would not be to their advantage. Yet, if you are in the Word of God, you will see that the true, loving shepherds spent much time teaching and warning the sheep to stay away, far away, from false leaders.
Rule #1: They do not look like false leaders to the physical eye. They do not sound like false teachers to the unskilled ear. The Apostle Paul told us, "For such men are false apostles, deceitful workmen, masquerading as apostles of Christ. And no wonder, for Satan himself masquerades as an angel of light. It is not surprising, then, if his servants masquerade as servants of righteousness" (2 Corinthians 11:13-15). It was not surprising to the studious disciples of Paul's day. However, if Jesus said there would be "many," then who have you identified?
Rule #2: If the only way for someone to go to heaven is to DO the will of God (1 John 2:17), then Satan's servants are brilliant, because they have made themselves look like religious teachers, and yet they have not secured your foundation. And many will make sure that true teachers are called "heretical" or "cult leaders." Jesus confronted the religious teachers and the counterfeit church in His day, calling them a "brood of vipers," saying "Woe to you, teachers of the law and Pharisees, you hypocrites! You travel over land and sea to win a single convert, and when he becomes one, you make him twice as much a son of hell as you are!" (Matthew 23:15) Jesus also warned the people that the preachers of the day had taken away the key to salvation. 
The key to salvation is DOING the will of God, and sneaky Satan and his servants will subtly excuse you from having to "do" the will of God-they even imply that it takes away from God's free gift of grace! How dangerous to play around with the only way to enter the kingdom of God.
The second major problem is that there are actually some false teachers who say, "do the will of God," but they push legalistic man-made rules. Once again, man is ruling, and not God. You need to stay in the Word of God and get yourself around a fellowship that has a great fear of false teachings. Please study the diagram to the left.
Please call us for more information about identifying a false leader. The main thing to know is to BE AFRAID. Stay away from them!