'Children' in the Bible

The Spirit Himself bears witness, along with our own spirits, to the fact that we are children of God;

and if children, then heirs too--heirs of God and co-heirs with Christ; if indeed we are sharers in Christ's sufferings, in order that we may also be sharers in His glory.

Yet there was always the hope that at last the Creation itself would also be set free from the thraldom of decay so as to enjoy the liberty that will attend the glory of the children of God.

nor because they are Abraham's true children. But the promise was "Through Isaac shall your posterity be reckoned."

In other words, it is not the children by natural descent who count as God's children, but the children made such by the promise are regarded as Abraham's posterity.

Nor is that all: later on there was Rebecca too. She was soon to bear two children to her husband, our forefather Isaac--