Postmillennialists like to point out that leaven doesn’t always represent evil or corruption, which is true enough. But it’s hard to avoid the fact that leaven often does represent evil. That might form some of the background to Jesus’ parable of the leaven.

David Garland writes: “The parable is not simply a meditation on insignificant beginnings. No reference is made to the small amount of leaven as in 1 Corinthians 5:6 and Galatians 5:9. To compare the kingdom of heaven to leaven is to invert the common images of sacred and profane . . . . It would be like saying that the kingdom of heaven is like ‘rust’ or a ‘virus.’ It is a rather iconoclastic image, but it accords with Jesus’ assertion that the tax collectors and harlots enter into the kingdom of heaven before the chief priests and elders (21:32) and Matthew’s conviction that one must believe that the kingdom has come in Jesus, the son of God who was crucified. The question is not: ‘Can something so contemptibly small be representative of the work of God?’ but ‘Can something so contemptible be representative of the work of God?’”

Postmillennial interpretation of the parables has to beware of stumbling over the offense of the cross.