“Now we, brethren, as Isaac was, are children of promise. But, as he who was born according to the flesh then persecuted him who was born according to the Spirit, even so it is now. Nevertheless what does the Scripture say? ‘Cast out the bondwoman and her son, for the son of the bondwoman shall not be heir with the son of the freewoman.’ So then, brethren, we are not children of the bondwoman but of the free”

Paul now turns to apply his illustration of verses 21-27 to the Galatians (4:28-31).

4:28

Now we, brethren, as Isaac was, are children of promise.

Paul now applies the illustration of verses 21-27 to the Galatians and thus to Christians (“brethren”). He makes three comparisons.

First, Paul compares Isaac’s physical birth to the Galatians’ spiritual birth (“children of the promise”). Christians become Christians through “promise.” Isaac came to this world as a result of a “promise” to Abraham. Christians become Christians and live the Christian life by the promise of God’s grace. The central point in Isaac’s birth is that his birth depended on God entirely, for it was the work of God and not the work of Abraham or Sarah. On the other hand, Ishmael’s birth was the work of human beings.

4:29

But, as he who was born according to the flesh then persecuted him who was born according to the Spirit,

The second comparison is Ishmael’s harassment of Isaac (Genesis 21:8-10). Ishmael was an Arab. This conflict between the first Arab (Ishmael) and the second Jew (Isaac) continues to this day.

even so it is now.

Legalists always persecute grace-oriented people because grace and legalism are polar opposites. Christians should expect opposition from legalists. It is amazing how people hate the grace of God.

4:30

Nevertheless what does the Scripture say? “Cast out the bondwoman and her son, for the son of the bondwoman shall not be heir with the son of the freewoman.”

Paul makes a third comparison between the expelling of Hagar and Ishmael by Abraham and the responsibility of Christians to reject legalism. Paul alludes to Sarah’s words, “Cast out the bondwoman” (Genesis 21:10). The Galatian Christians needed to deal firmly with legalistic Judaizers. They needed to “cast” legalism out of their midst. Legalism and grace cannot co-exist together because one negates the other.

If people do not receive grace, then there is no hope for them. All that is left is for God to throw them out. We cannot receive anything from God except through grace.

4:31

So then, brethren, we are not children of the bondwoman but of the free.”

Dynamic Christians do not follow legalism but grace. Grace-oriented people are people who trust in Christ alone, by faith alone. They are, therefore, free in their relationship to God because of Christ.

Principle:

Grace and legalism cannot co-exist together.

Application:

Grace and legalism cannot co-exist at the same time. The very idea of the one excludes the other. Either we please God by what we do, or we appropriate what Christ did to please God. It is either one or the other, not both.

Legalists do not like grace-oriented people because grace humbles the believer. Legalism points to self and self-righteousness. Grace points to the finished work of Christ. One is self-effort; the other is Christ-effort. The two ideas are diametrically opposed. We tend to confuse the two. They are as different as black and white, yet some Christians try to merge them together. The law always presents stipulations to fellowship with God. Grace has no provisos. Legalists hate grace people because it is not trendy to humble one’s pride.

Legalism always results in slavery. As long as we have one foot in grace and one foot in legalism, we are in bondage. Christ redeemed us from the curse of the law. When we go back to the law, we diminish Christ’s death for our sins.