All the children of God are the children of promise.

See the freedom and sovereignty of the grace of God, in the adoption of any child to himself. Why, all his children are children of promise, as Isaac, who was not born by the strength of nature; for Abraham and Sarah were both old, and his body was dead, and her womb was barren; and, besides natural barrenness, she was past the prolific age; so that Isaac was not born by the strength of nature, but merely by the virtue of the promise: so believers are made the children of God, not by the power of nature, but by the virtue of the promise, when the Spirit of God puts a generative virtue therein. It is the promise of God in Christ, that makes us children; and the promise is of the mere free grace of God; therefore they that are God's children, are so by the mere free grace of God; "Having predestinate us the adoption of children by Jesus Christ to himself, according to the good pleasure of his will, to the praise of the glory of his grace, wherein he hath made us accepted in the Beloved," Eph. i. 5. How dishonourable then to the doctrine of God's free grace and sovereignty is it, for any to assert, "That election and adoption is according to God's fore-knowledge of our faith and obedience?" For, thus would we elect ourselves, and be children, not by divine promise, but of our own free-will and faith. God foresaw the faith of his elect, indeed, because he first decreed to give the grace of faith to them; for the foreknowledge of things to come to pass, depends upon a precedent will in God; nothing comes to pass without his will. The friends and favourites of the free-will of man, in converting themselves, are enemies to the free grace of God in begetting children to himself, by virtue of his promise in Christ, and by the means thereof. Neither does this abolish the freedom of the will; for, as the generative promise is just the absolute will of God, so the determination of man's will by the will of God, is the liberty of the will, and not the bondage of it: when he works powerfully on the will of man, he gives both to will and to do, he makes the man willing; and this is the perfection of liberty, when man's will is made conform to the will of God.—Thus all the children of God are the children of promise.

—Ralph Erskine, The Pregnant Promise.