Your boasting is not good. Don’t you know that a little yeast works through the whole batch of dough? Get rid of the old yeast that you may be a new batch without yeast—as you really are. For Christ, our Passover lamb, has been sacrificed.
1 Corinthians 5:6-7
One of my oldest friends, Fiona, is training to be a doctor. Several years ago, just as she was starting her studies, she persuaded me to join Facebook. I had no idea what Facebook was, and even less of an idea what it was for, but I duly joined. For over a year, Fiona was pretty much my only friend on Facebook. Then, slowly, over the next few months, more of my friends began to join up, and I gradually began to get a better idea what Facebook was for. A short while later, pretty much everyone I knew was on Facebook, and everyone was talking about this new internet sensation. It grew very quickly from a small affair to something that seemed to catch the interest of the whole world.
Facebook is a perfect example of something that affects a whole community. It only needs a few people to lead the way, and suddenly everyone is involved. Communities can be good at spreading these positive events. But communities can also use this effect for negative purposes. You often find that when a couple of people in a group of friends start smoking, many of the other friends start too. It’s a slippery slope, and we need to be careful of the power of communities to spread ideas. In today’s reading, Paul stresses this to the Corinthians. He is only too aware of the power of communities. He uses the metaphor of yeast and dough. A little yeast can affect a large batch of dough. Similarly, sin can affect a whole community. It only takes a few people to commit the same sin for society to redefine this as acceptable behaviour.
Jesus uses exactly the same metaphor in our current Mark Marathon passage. He warns his disciples of the dangers of the “yeast” that is Herod and the Pharisees. They will try to mislead people and undermine the teachings of Christ.
There’s an important lesson for us here. We must not simply go along with the crowd, especially not as far as our faith is concerned. Instead, we must ensure that our faith is based on something solid – the teachings of Christ and wider scripture. Make sure that you don’t allow yourself to mislead by the false teachings of others.