28 Now we, brethren, as Isaac was, are the children of promise. 29 But as then he that was born after the flesh persecuted him that was born after the Spirit, even so it is now.
English Standard Version
28 Now you,Some manuscripts we brothers, like Isaac, are children of promise. 29 But just as at that time he who was born according to the flesh persecuted him who was born according to the Spirit, so also it is now.
28 Isn't it clear, friends, that you, like Isaac, are children of promise? 29 In the days of Hagar and Sarah, the child who came from faithless connivance (Ishmael) harassed the child who came - empowered by the Spirit - from the faithful promise (Isaac). Isn't it clear that the harassment you are now experiencing from the Jerusalem heretics follows that old pattern?
New King James Version
28 Now we, brethren, as Isaac was, are children of promise. 29 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.
New Living Translation
28 And you, dear brothers and sisters, are children of the promise, just like Isaac. 29 But you are now being persecuted by those who want you to keep the law, just as Ishmael, the child born by human effort, persecuted Isaac, the child born by the power of the Spirit.
The history thus explained is 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, according to the new covenant, how absurd for the Gentile converts to be under that law, which could not deliver the unbelieving Jews from bondage or condemnation! We should not have found out 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. It is an explanation of the subject, not an argument in proof of it. The two covenants of works and grace, and legal and evangelical professors, are shadowed forth. Works and fruits brought forth in a man's own strength, are legal. But if arising from faith in Christ, they are evangelical. The first covenant spirit is of bondage unto sin and death. The second covenant spirit is of liberty and freedom; not liberty to sin, but in and unto duty. The first is a spirit of persecution; the second is a spirit of love. Let those professors look to it, who have a violent, harsh, imposing spirit, towards the people of God. Yet as Abraham turned aside to Hagar, so it is possible a believer may turn aside in some things to the covenant of works, when through unbelief and neglect of the promise he acts according to the law, in his own strength; or in a way of violence, not of love, towards the brethren. Yet it is not his way, not his spirit to do so; hence he is never at rest, till he returns to his dependence on Christ again. 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.