The parable of the wheat and weeds has been overshadowed by Matthew's tendency to bring in statements of threat and judgement in several places in his gospel. This is likely part of the reason why the Church has, over the course of its history, resorted to violence and other ways of dealing with those perceived as "weeds" in the Church, all in the name of protecting those perceived as the "wheat." But Jesus makes it plain in this parable that this is not our call to make...
NOTE: the two references to "red and blue" in the sermon relate to the children's talk Rev Derwyn delivered earlier in the service.