7 Neither, because they are the seed of Abraham, are they all children: but, In Isaac shall thy seed be called.
7
Nor because they are his descendants are they all Abraham’s children. On the contrary, “It is through Isaac that your offspring will be reckoned.”
8 That is, They which are the children of the flesh, these are not the children of God: but the children of the promise are counted for the seed.
8
In other words, it is not the children by physical descent who are God’s children, but it is the children of the promise who are regarded as Abraham’s offspring.