The wheat and the weeds
The first of the parables, like last week's reading, is often used by people to justify their views of predestination. In it a farmer plants good seed in his fields, but his enemy plants weeks in the farmer's field while the farmer is sleeping. The farmer allows both wheat and weed to grow together out of concern that pulling up the weeds might also kill good plants. Instead, he lets them grow together and only separates them at the harvest.
It's easy to see why this would lead people to the idea of predestination as the good and bad are determined when they are still seeds (this is also where the expression a "bad seed" when referring to a person can be traced back to). Yet what most followers of predestination miss is that the farmer allows the wheat and weeds to live together. This was Jesus's answer to why evil is allowed to exist in the world. He is not willing to damage (or even mistakenly destroy) the good people just to rid the world of evil. There is also a suggestion that it is not fully possible to discern the wheat from the weeds. While people might judge one another as evil or worthy, only God knows the final outcome, and thus only He is the proper judge.
In the sermon today, we were told that the wheat and weeds can also be taken to look at the experiences in our lives. We have time to still nurture the proper tendencies and feelings within us. This idea connects to the last two parables which deal with faith being compared to a mustard seed (which might start as a small seed, but can grow into a large plant that gives others rest) and to yeast (which only needs a little to help a large amount of dough to rise).
Too many people focus on the part of the burning and the "wailing and gnashing of teeth" and not enough of the nourishing and hopeful side of these teachings. We have to allow the seeds of faith to grow within us, not just for our lives but for the lives that we touch.