But he said, Nay; lest while ye gather up the tares, ye root up also the wheat with them. Let both grow together until the harvest: and in the time of harvest I will say to the reapers, Gather ye together first the tares, and bind them in bundles to burn them: but gather the wheat into my barn.”
This parable, which is explained by Jesus in verses 37-43, tells us that the devil is always here to over-sow the world. Wherever the gospel is preached, the devil plants unbelievers among the believers. There will always be the fake and the insincere, until the end of time. It is not our duty to get the tares out of the world; however, as much as possible, we should keep the church pure. God will separate the wheat from the tares in the final judgment. We might be fooled about the identity of the wheat as opposed to the tares, but in God’s judgment all will come to light and be rectified.
A little noticed fact in this parable is that the final judgment will not take place until it happens in the earthly kingdom of the Lord Jesus Christ (see verses 41 and 43). We know from the Book of the Revelation that it will take place right at the end of the Thousand Year Reign of Christ (the Millennium, see Revelation chapters 19 and 20). All of the Children of God will go into eternal bliss; but sadly, the unsaved will be cast into the Lake of Fire.