The words that grabbed my attention are "goes beyond it." That phrase translates the Greek word parabaino, which literally means "off base." Here is a person who goes "off the base" of Christ's teaching. The teachings of Christ, and His apostles, constitute the sure foundation of correct doctrine. False doctrine goes off that foundation.
But notice: that does not mean they started on the wrong foundation. They may have started on the correct foundation, but they were not content to stay there. They kept moving until they went off that base.
This is a brand of false teaching that is especially deceptive. The most damning error is that which sounds most like the truth. Satan is no fool. He has learned to be an expert at his craft--and he has trained his servants well in his methods. He tickles the oyster before he sticks in his blade. He lures his victim with tantalizing bait, then he springs the trap! Any false teacher worth his salt knows you don't begin by spouting lies. Any half-conscious Christian will--hopefully--recognize the lies and turn him off immediately. So he begins... where? With the truth! He draws us in. Hearing what is familiar causes us relax our defenses. The false teacher may use humor--an extremely effective tactic--or well rehearsed stories. He tells us that "God is love," and "Jesus was a great teacher." Then, drawn into his message, he gives us a smidgen of his error. There may be an instant when we are alarmed. A red light begins to flash on the dash of our soul. But before we can process what the false teacher just said he passes on to the next story... or joke... or maybe--blast his eyes--truth, and before our defenses can go completely up they're down again. I'll say it again: the most dangerous brand of error is the one which sounds most like the truth.
So how do we protect ourselves from error?
First, we must remain vigilant. We must hold ourselves and our brothers and sisters in Christ accountable. We must ask ourselves and each other a simple question: "Is that right?" We must compare the words of our teachers with the words of truth--because those two things may not be the same.
Second, we must train ourselves to know the truth. The best defense against error is not to study false religions, but to know the truth. Those who are experts at detecting counterfeits do not spend their time studying copies. They study the genuine article--because if you know the real thing you won't be fooled by a clever copy!
Third, consider their fruit. What is the fruit of this teacher's ministry? Is it Christians who are mature and well-grounded in the truth themselves? Does he encourage his followers to read the Bible and listen to other godly teachers? Or does he produce a brand of followers who are squishy in their theology?
Fourth, look at his character. Does the teacher live the truth he teaches? Of course he is not perfect, but does he pursue a godly lifestyle? This is one reason why we need teachers who live and walk among us--so we can observe their lives. A leader reproduces what he is.
Finally, lets go back to where this began and remember this: it is not where the preacher begins that is the test of his teaching, but where it ends up. Satan's most effective teachers begin with the truth, but they don't stay there. From that point they steer off the foundation. So stay on your toes at all times "because your adversary, the devil, is on the prowl, looking for someone to devour" (1 Peter 5:8).