Nothing good has ever come into the world without opposition, and that is especially true in spiritual matters. Here we face not only the hostility of mere people like ourselves but satanic opposition as well. That is why the Bible warns us to be on our guard against the devil, who, we are told, “prowls around like a roaring lion looking for someone to devour.” The Scripture alerts us to the devil’s “schemes,” because he must not be allowed to “outwit us.”
Since we have an enemy who is so fiercely opposed to the extension of God’s rule on earth, we should not be surprised to find the Lord warning us against his devices in the parables of the kingdom in Matthew 13. Jesus does this clearly in the second parable, showing how the devil, like the enemy of a certain farmer, sows weeds in God’s field, meaning that he scatters non-Christians among believers. The weeds of this parable are almost certainly a plant called bearded darnel, which is closely related to wheat and is difficult to distinguish from it when the plants are young. Moreover, the roots of the two plants entangle themselves so that pulling up one would necessarily mean pulling up the other. When the plants are older, it is easy to tell them apart. According to the parable, the separation will come only at the final judgment.
What is the point of the devil planting children “in the world,” if all it means is that the devil’s children and God’s children live side by side? If that is what Jesus means, the parable is not even stating the situation in the best way. If the field is the world rather than the Church, it would be more correct to say that the devil’s people are in the world already and that it is Jesus, rather than Satan, who plants His seed among that which is already growing. It would be Jesus who does the new thing, not Satan. However, as Jesus tells the story, the point is what Satan is doing, and that is something done after Jesus has already sown his seed. In other words, the devil places his own counterfeit Christians among true believers to hinder God’s work.
So that is the real message, and whether the field is the world or the Church is actually irrelevant. The point is simply that the devil is going to bring forward people (whether in the Church or out of it) so much like true Christians, though they are not Christians, that even the servants of God will not be able to tell them apart. Consequently, although we want a pure Church and will certainly exercise Church discipline to the best of our ability in clear cases, we must not think we will achieve our full desire in this age. Even in our exercise of valid Church discipline we must be extremely careful not to discourage or damage some for whom Christ died.
Notice first, If the devil is mixing his people in among true Christians, then we should be alert to that fact. We should be on our guard not to be taken in by those who pretend to be Christians but are not, and we should not be surprised if the devil’s people show up in strange places or eventually show their true colors by abandoning Christianity entirely. In Second Corinthians Paul gives just such a warning, pointing out that “Satan himself disguises himself as an angel of light” and that “it is not surprising, then, if his servants disguise themselves as servants of righteousness” (II Co.11.14-15). “Servants of righteousness” can describe ministers. So, we have a proverb that says rightly, “When you look for the devil, don’t forget to look in the pulpit.”
Again, we are not to be surprised if some eventually repudiate the faith and leave the Christian fellowship. John also wrote about such people, saying, “They went out from us, but they were not of us; for if they had been of us, they would have continued with us. But they went out, that it might become plain they all are not of us.” (I Jn. 2.19).
Second, the mixed nature of the Christian assembly should not be an excuse for unbelievers to refuse to come to Christ. Jesus did not pretend (nor should we) that the Christian Church is perfect. It is anything but. Sometimes those who are not Christians say, “I’m not a Christian because the Church is filled with hypocrites.” But that is itself a hypocritical statement. It implies that the one making it is better than those whom he rejects, which is probably not true. At best it is not the whole truth since there are deeper reasons why people will not become Christians. Still, the real problem is that if the objection were to be met (that is, if hypocrisy and other sins were to be completely eliminated among the people of God), there would be no place for the objector! The critic, who is himself a sinner and a hypocrite, would not fit in. There is a place for him only because Jesus came “not … to call the righteous, but sinners” to repentance (Mt.9.13).
Finally, No one should take comfort in sin. The Church is impure because, as Luther said, every Christian is at the same time righteous and a sinner. We cannot always distinguish between the wheat and tares in this age. But a day is coming when that distinction will be made. The harvest will happen, the wheat will be gathered into God’s barn, and the tares will be burned. As a result, we should examine ourselves as to whether we are true children of God or not. We should be careful to make our “calling and election sure,” as Peter says in his second letter.