Persecution by the Legalists

Paul's application of the allegory of Hagar and Ishmael has already compared the Judaizers and legalists in a very bad light, as corresponding to Hagar and Ishmael, the child of the flesh, born under bondage. So too the legalists are in bondage to Sinai's law, while Gospel believers are compared to Isaac, born in liberty, the children of promise born of the faith of Abraham in the promised sacrifice, the Lord Jesus.

Paul then applies a passage rejoicing in the barren woman's fruitfulness. It had appeared that the works of the flesh and of law-keeping would provide children to fill up the promises God made to Abraham. As with Hagar, so with the legalists: they gloated at the fruitfulness of the law.

But when the true noble seed were finally revealed in Christ's Gospel, and Gentiles were brought into God's family by faith without works, then the rejoicing was magnified for the children of promise. Grace is fruitful, while law-works are shown to be barren.

Paul then points out that legalists persecute the true children of promise, just like Ishmael mocked little Isaac. The legalists excluded true believers, claiming falsely they were not true children of Abraham and sons of God. That persecution has often descended into violence against God's people, both in Paul's day and in more modern times under Roman Catholic persecution.

Any teaching against the Gospel, adding law-works for righteousness, is a mocking of Bible Christianity, a belittling of the true children of God.

The Lord Jesus warned of persecution by the Jews and others, but He promised not a hair of our heads would perish, because we trust only in His obedience and blood for our eternal redemption!