Jesus told a parable about an evil person who had sown seeds of weeds in a wheat field, while the farmer slept (Matthew 13:24-26).  When servants found weeds shooting up among the corn, they told the estate owner: they did not know how the wheat seed had been contaminated.  However, the owner knew that he had authorised the very best seed to be sown, and therefore the weeds had been deliberately sown by an enemy.
 
What should they do, they asked?  Should they go through the field and pull up all the weeds?  But if they did, they would trample the developing corn; and as the roots were intertwined, the wheat would be removed with the weeds.  It was a strong desire, like that of James and John who wanted to call down fire to consume unbelievers (Luke 9:51-56); but Jesus rebuked them.  The owner was not willing to risk losing even one shoot of corn.  He was so confident that the good crop was strong enough to survive the competition from the weeds, that he ordered the servants to leave the field alone until harvest time.
 
And so, good and bad plants grew together: the true believers and those who God could never honour (Matthew 7:21-23).  The separation between the righteous and the wicked was done once both had reached their full potential - as was God’s judgement on the wicked in the Promised Land (Genesis 15:16).  Eventually, the weeds could no longer be tolerated and would be destroyed. However the good corn would be carefully collected and stored in the owner's barn. The meaning is clear.  The field represents the people of the world.  Those who receive the good seed of the gospel are the children of God's kingdom, but the weeds are the children of the Evil One.  Every person is either one or the other.
 
God allows both good and evil people to coexist in His world.  Some say that a balance of good and bad is healthy - it is not.  But the apparent vigour of evil will not last for ever.  It has no value to God and will be destroyed, so that His eternal home will be completely free from all corruption.  That will happen when Jesus Christ returns.  Meanwhile, it is important to understand that the evil in the world is not from God, but from His enemy the devil.  But Satan does not have the last word - God is the owner of the world and has the right to determine the destiny of every person.  Only those who receive the good seed of the gospel and welcome Jesus will be welcomed by Him.