Not only are there two ways (former blog), but there are two kinds of prophets as well. Jesus speaks directly of the one that is false and implies something about the other.
Christians in the primitive church were especially vulnerable to false prophets who taught another gospel. They did not have ready access to written documents nor did they have the benefit of hundreds of years of theological teaching regarding the truths to which they had committed themselves. Jesus described the false prophets as “ferocious wolves” that acted like sheep. They took the truths of scripture and twisted them for personal profit. False teaching is more than an accidental departure from truth; it is an intentional alteration of truth for personal gain. Jesus warns the church about these deceptive wolves by telling the believers how they can spot them. It isn’t difficult; simply look at their lives. Actions have always revealed whether a teaching is true or false – “You will know them by what they do” (v. 16). If the fruit is good the tree is healthy; if the fruit is bad the tree is worthless and ready to be cut down and burned up (v. 19).
Let’s think for a moment about the deceptive nature of error. To convince oneself that the desire for possessions is positive, one could say, “See how well such and such a Christian project is doing because of my financial help.” What is not said is how the money was gathered or how much was spent to get it. Token gifts have allowed considered significant personal benefit and have provided and excuse for cultivated greed. Charity Navigator is an excellent site to find out all you need in order to evaluate a given not-for-profit organization. All of us are deluged from time to time with “opportunities to be of help.” Opportunities to donate are so cleverly stated that many fall for them. A very wise minister in a large church once told me that God always finances what he initiates. Lest I be misunderstood as being against charitable organizations I need to add that concern to guard what you have earned is not necessarily wrong. I want my dollars to go where they can go to work for those who need help. My concern is the deceptive nature of so much advertizing.
So John says, “Watch out for false prophets,” whether one is dealing with basic truths of the church or the life style of their proponents. Remember, you can recognize them by what they do, or, in biblical language, “by their fruit you will recognize them” (v. 20).