(Rom 9:7) “Neither, because they are the seed of Abraham, are they all children: but, In Isaac shall thy seed be called. (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. (9) For this is the word of promise, At this time will I come, and Sara shall have a son.” Notice closely the wording of verse 8, “…children of the flesh….not the children of God…” God is a Spirit, and therefore His children are spirit, made so through a rebirth. This is a miraculous moment when the Holy Spirit gives life to the dead spirit of a person. It comes through humble repentance and desire: (Psa 51:17)”The sacrifices of God are a broken spirit: a broken and a contrite heart, O God, thou wilt not despise.”