When Jesus tells the parable of the weeds and the wheat to the crowds, the point was that the growth of the kingdom requires patience. We should not try to anticipate God’s judgment.
When Jesus explains the parable to His disciples, the point seems different. Now the emphasis seems to be on the threat of stern judgment for sinners at the end of the growing season.
The common point of both versions of the parable seems to be that the growth of the kingdom involves judgment, a judgment that only God can make, that involves the moral quality of those being judged.
We are in the field of God’s kingdom, growing toward the harvest that will surely come. Are we the wheat or the weeds?