1 Cor 5 If you have ever made bread, you know it doesn’t take much yeast to make it rise. Two teaspoons mixed in about six cups of flour will make two large loaves of bread because the yeast permeates the entire dough. In scripture, yeast represents sin, and just like in bread dough, that sin will permeate the whole batch of dough or the church. Perhaps that is why God commanded that it be unleavened bread for the communion table. To be a pure church, we must eradicate or remove the yeast of vice and evil.
The yeast of immorality existed in the Corinthian church, tainting its purity. To be pure, the church must not associate with sexually immoral people. Instead, they should have judged this sin, remove it, and the person or persons living this lifestyle. But, the Corinthian church not only allowed this immorality to co-exist, but they also did not condemn it. All we need to do is read Revelation’s second and third chapters to see how devastating sin is to a church. First, it loses its first love, then fear which is a snare, creeps in, then that sin becomes a stumbling block, and finally, false teaching taints the body.
Precious believers, be wise as serpents and harmless as doves as you discern and judge sin. Keep yourselves pure, and the church will be pure.