Children of God are not defined by what they do but by what God says about them. God called Abraham a father and Sarah a mother of nations before they had a child. They were a father and mother of nations, not because they had children to prove it, but because God had declared them so. Since He is God and His word never fails, what He said of them proved to be true in the long run.
Are we willing to believe and declare what God has spoken about us? Are we willing to accept His word as our identity and reality even before we see any manifestation?