All who are led by God's Spirit are God's sons.
For you did not receive a spirit of slavery to bring you back again into fear; on the contrary, you received the Spirit, who makes us sons and by whose power we cry out, "Abba!" (that is, "Dear Father!").
The Spirit himself bears witness with our own spirits that we are children of God;
and if we are children, then we are also heirs, heirs of God and joint-heirs with the Messiah - provided we are suffering with him in order also to be glorified with him.