The children born in the natural way (literally “the children of the flesh”) is not a reference to the manner of birth (that is, to natural birth as opposed to caesarean birth, for example), but rather a reference to “physical descent” (so Jerusalem Bible).

There are real difficulties involved in any type of literal translation of “the children of the flesh” or the children born in the natural way, since such expressions are likely to be misunderstood. In some languages one may render such a construction as “this means that not all of Abraham’s children were to be considered the children of God” or “… not all the children of whom Abraham was father are to be considered God’s children.”

God’s promise (so New English Bible) is literally “the promise,” but the reference is to God’s promise.

The phrase as a result of God’s promise may be rendered as “because God specifically promised them”—for example, “but only the children born to Abraham, because God had specially promised them to him, are to be called Abraham’s descendants” or “… true descendants.” True descendants is literally “descendants,” which the New English Bible takes to mean “Abraham’s descendants.” However, in the context the meaning seems rather to be that the children born to Abraham as a result of God’s promise are “God’s descendants” (see Moffatt “His true offspring”).

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 .