Matthew Henry Commentary Galatians 4:28-31

"Now we, brethren, as Isaac was, are children of promise. But as then he that was born after the flesh persecuted him [that was born] after the Spirit, so also it is now. Howbeit what saith the scripture? Cast out the handmaid and her son: for the son of the handmaid shall not inherit with the son of the freewoman. Wherefore, brethren, we are not children of a handmaid, but of the freewoman." — Galatians 4:28-31 (ASV)

This history, having been explained, is now applied. So then, brethren, we are not children of the bond-woman, but of the free. If the privileges of all believers were so great under the new covenant, how absurd it would be for the Gentile converts to be under that law, which could not deliver the unbelieving Jews from bondage or condemnation! We would not have discovered this allegory in the history of Sarah and Hagar if it had not been shown to us; yet we cannot doubt it was intended by the Holy Spirit.

This is an explanation of the subject, not an argument to prove it. The two covenants—of works and of grace—and the contrast between legalistic and evangelical believers, are foreshadowed here.

Works and fruits produced in a person's own strength are legalistic. But if they arise from faith in Christ, they are evangelical. The spirit of the first covenant is one of bondage to sin and death.

The spirit of the second covenant is one of liberty and freedom—not liberty to sin, but liberty in and for duty. The first is a spirit of persecution; the second is a spirit of love. Let those professing Christians who have a violent, harsh, imposing spirit towards the people of God take heed.

Yet, just as Abraham turned aside to Hagar, so it is possible for a believer to turn aside in some things to the covenant of works. This can happen when, through unbelief and neglect of the promise, they act according to the law in their own strength, or in a way of violence, rather than love, towards their fellow believers.

Yet it is not their way, nor their spirit, to do so; therefore, they are never at rest until they return to their dependence on Christ. Let us rest our souls on the Scriptures and, by a gospel hope and cheerful obedience, show that our conversation and treasure are indeed in heaven.