This verse functions not only as the climax of Paul’s argument in this section, but picks up again the theme started in verse 7 and referred to again in verses 9, 14, and 16, namely, the question of who are the real descendants of Abraham. The condition for becoming a descendant of Abraham is here stated differently, but the meaning is the same: if you belong to Christ. The if does not introduce a mere hypothesis, but it suggests that what follows is true and certain (compare Jerusalem Bible “merely by belonging to Christ”). Since this condition does imply an actual fact, it may be expressed more accurately as a condition of cause, for example, “because you belong to Christ, then you are the descendants of Abraham,” or “… belong to the lineage of Abraham.”

Will receive what God has promised is literally “heirs according to the promise.” As in verse 18, the inheritance implied in the word “heirs” is the gift of God, the content of God’s promise, and therefore the “heirs” are the recipients of God’s promised gift. It may, moreover, be necessary to specify those to whom the promise was made, for example, “will receive what God has promised to you as descendants of Abraham,” or “will receive what God has promised Abraham’s descendants,” or even “… Abraham and his descendants.”

Quoted with permission from Arichea, Daniel C. and Nida, Eugene A. A Handbook on Paul’s Letter to the Galatians. (UBS Handbook Series). New York: UBS, 1976. For this and other handbooks for translators see here .