The first part of this verse reads literally: “neither are all Abraham’s descendants children.” It is not clear whether Paul intends “children” to mean “Abraham’s children” or “God’s children.” On the basis of the following verse, the Good News Translation understands this to be a reference to the children of God (see also the New English Bible alternative rendering); others make it a clear reference to Abraham’s children. But even if “Abraham’s children” is intended, there should be some type of qualifier (New English Bible and Jerusalem Bible have “his true children”). Since the initial clause of verse 7 introduces a further example of a special relationship of people to God, it may be useful to introduce this clause by a conjunction like “moreover” or “furthermore.” There is a distinct problem in saying that “not all those who descended from Abraham are the children of God.” Such a rendering might seem to be entirely too general, particularly in view of the fact that the people referred to are actually “children according to God’s promise.” It may be necessary, therefore, in some languages to render this phrase as “the true children of God,” or “the children whom God promised to Abraham.”

Having introduced the major point in his argument, Paul now appeals to scripture to strengthen it. The reference is to Genesis 21.12, and Paul quotes from this verse without any introductory formula except the conjunction “but” (see Revised Standard Version). The Good News Translation makes it clear that the promise is something that God said to Abraham, a fact which is not made explicit in most translations.

The descendants of Isaac will be counted as yours may be translated as “only the offspring of Isaac will be counted as your offspring” or “only those who belong to Isaac’s family will be counted as your children.”

Quoted with permission from Newman, Barclay M. and Nida, Eugene A. A Handbook on Paul’s Letter to the Romans. (UBS Handbook Series). New York: UBS, 1973. For this and other handbooks for translators see here .