I was asked about this parable by a friend of mine. He asked what it meant. He had some idea, but felt like some thing was missing in his understanding. I figured I would share this with the rest of you as well.
The Parable of the Weeds  He put another parable before them, saying, “The kingdom of heaven may be compared to a man who sowed good seed in his field,  but while his men were sleeping, his enemy came and sowed weeds among the wheat and went away.  So when the plants came up and bore grain, then the weeds appeared also.  And the servants of the master of the house came and said to him, ‘Master, did you not sow good seed in your field? How then does it have weeds?’  He said to them, ‘An enemy has done this.’ So the servants said to him, ‘Then do you want us to go and gather them?’  But he said, ‘No, lest in gathering the weeds you root up the wheat along with them.  Let both grow together until the harvest, and at harvest time I will tell the reapers, Gather the weeds first and bind them in bundles to be burned, but gather the wheat into my barn.’” (Matthew 13:24-30 ESV)
Who are the weeds, Who are the wheat? Well, to start off, we look a few verses later in the same chapter and we see this passage:
The Parable of the Weeds Explained
 Then he left the crowds and went into the house. And his disciples came to him, saying, “Explain to us the parable of the weeds of the field.”  He answered, “The one who sows the good seed is the Son of Man.  The field is the world, and the good seed is the sons of the kingdom. The weeds are the sons of the evil one,  and the enemy who sowed them is the devil. The harvest is the end of the age, and the reapers are angels.  Just as the weeds are gathered and burned with fire, so will it be at the end of the age.  The Son of Man will send his angels, and they will gather out of his kingdom all causes of sin and all law-breakers,  and throw them into the fiery furnace. In that place there will be weeping and gnashing of teeth.  Then the righteous will shine like the sun in the kingdom of their Father. He who has ears, let him hear. (Matthew 13:36-43 ESV)
We, as humans on earth are able, at times, to tell the difference between the weeds and the wheat. Jesus tells his disciples the following in John 13:34-35:
 A new commandment I give to you, that you love one another: just as I have loved you, you also are to love one another.  By this all people will know that you are my disciples, if you have love for one another.” (John 13:34-35 ESV)
But for the most part, we who belong to God are living the same as those who dont, We can not tell the difference. The point is that it is not our job to separate the wheat from the weeds, it is out Jesus job. He will do it perfectly at the end of the days. Our job is to make sure that, first, we are the wheat, and second, that as many people as possible are the wheat. Our job is to tell people that the weeds will be burned up at the end and the wheat will “shine like the sun in the kingdom of their Father.”