Matthew 13:36 - 43
ESV - 36 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. 37 He answered, "The one who sows the good seed is the Son of Man.
For follow-up discussion and general commentary on the topic. Comments are sorted chronologically.
First of all the true church are those that have put their faith in Jesus blood sacrifice for their sins to save them. To them gave He power to become the sons of God, even to them that believe on His name. I believe according to scripture that the wheat and the tares are the true believers and the false in any denomination.
There are still many in all denominations that have never had a true born again experience. It is all about religion to them and they go to church, even pray and do good works. But they are trusting in their good works to save them. These are the tares that grow up together with the true believers. They are trusting in their own righteousness to save themselves.
It is hard to tell one from the other, but by their fruit we will know them. True believers are humble and kind, and do good works because they love Jesus for what He has done for us and not to save us.
They grow up together and may be hard to tell apart.
It could also be the true saints and the rest of the world like Michael said. Either way it is still true believers and unbelievers. The tares and the wheat.