Here is another story Jesus told: "The Kingdom of Heaven is like a farmer who planted good seed in his field. But that night as the workers slept, his enemy came and planted weeds among the wheat. (Matthew 13:24-25)
Jesus told a story known as the parable of the wheat and tares. In this particular story, He talked about a farmer who planted a crop of wheat. And during the night his enemy, probably a competitor, came along and sowed tares, or weeds, among the wheat.
The tare that Jesus described in this parable was also known as the darnel seed, which looks almost exactly like wheat in the beginning stages of its growth. But after it grows a little more, it becomes evident that it is a weed, and it actually uproots the wheat.
When one of the farmer's workers asked him, "Shall we pull out the weeds?" the farmer replied, "No, you'll hurt the wheat if you do. Let both grow together until the harvest. Then I will tell the harvesters to sort out the weeds and burn them and to put the wheat in the barn."
Jesus told this story to point out that there are people in the church who have infiltrated our ranks. While there is wheat, there are also tares. We don't know who is who, necessarily. You will find them sitting side by side in a pew, breathing the same air, and singing the same songs. One may be a believer, while the other may be an unbeliever. One may be wheat, and one may be a tare.
We always will have people who infiltrate our ranks, the Ananiases and Sapphiras and the Judas Iscariots—the satanic plants that undermine the Word of God. But it is not our job to weed those people out. We don't see a person's heart. Our concern should not be who the hypocrites are, but whether we are hypocrites ourselves. Our job is to take care of ourselves, to take heed and make sure that we are true believers.
Taken from "Wheat and Tares" (used by permission).