Galatians 5:9 Commentary and Bible Study

The point of the illustration is the great effectiveness of the yeast even though it is added in a relatively small quantity to the lump of dough. Having been mixed throughout the dough by careful kneading, it causes the whole of the dough to rise under its influence. This is a picture of a small cause having a greater effect (Hendrickson). Leaven is used in Scripture to illustrate the effect of teaching, both good and bad. In a good sense, Christ uses it to describe the effect of the preaching of the gospel throughout the world (Matthew 13:33; Luke 13:21), but in an evil sense he warns against the teaching of the Pharisees (Matthew 16:6). Paul uses it of the doctrine of sin by which an unbeliever used to live (1 Corinthians 5:7-8). Here in Galatians 5:9 it is used to describe the pervasive effect of the false works-based salvation of the Judaizers; the spread of the false is insidious. It works its way into every part, and once it has been accepted its progress is very hard to stop so that it does damage to the entire theology of a man. The point is that all this starts from a little. Even a small amount of yielding to this fatal belief will do a great deal of damage, for the bad doctrine spreads throughout our belief system and though thinly spread, does much harm.