“For you did not receive the spirit of slavery to fall back into fear, but you have received the Spirit of adoption as sons, by whom we cry, ‘Abba! Father!’ The Spirit himself bears witness with our spirit that we are children of God, . . “ (Romans 8:15-16)
Paul speaks here about the flesh but refers primarily to the unregenerate human nature, not necessarily just the body. The flesh is human nature that stands opposed to God, is subject to sin, weakness, limitations, and death. The flesh cannot please God at all. Thus it is only by the indwelling Holy Spirit do we have spiritual life now and eternal life assured. And so since we have the new life by the Spirit, we ought to live it, for the Holy Spirit accomplishes what the law could never do because of our weakness and frailty. The Holy Spirit enables us to follow the Law of God. Though we follow imperfectly we now have a new relationship to God as sons. We now can come to Him freely.
The term “Sons of God” is quite radical. It indicates that the relationship that we have with the Father is the same relationship that He has with Christ, because He is the Son and we also are sons. We are not equal in nature but in relationship, in inheritance. The term applies to all Christians, men and women, slave and free, noble and commoner, celebrity and unknown. In Paul’s society, this would have been much more radical than we perceive now for then, in general, only male sons had rights, privileges, property and inheritance. Women were an inferior class. What Paul was saying was that there are no legal or social distinctions among Christians. All have equal rights before God in terms of access to Him, the blessings of the regenerate life and the assurance of the future eternal inheritance.
In our new relationship we can go to our Father without fear. We can call Him “Abba, Father” the same words used by Jesus when He prayed in the Garden of Gethsemane (Mark 14:36). These words were used in the context of the intimate family relationship, and were never used by the Jews to refer to God. But we can use them! We as children may always approach the Father and find a listening ear, comforting words and a helping hand. We have access to God, we have freedom from sin and we have the eternal assurance of life everlasting.