The Spirit you have received is not a spirit of slavery leading you back into a life of fear, but a Spirit that makes us sons, enabling us to cry "Abba! Father!" Rom. 8:15, N.E.B.
Many of us recall from the earlier decades of this century the sweet stories that were popular both in the fiction and the nonfiction markets. A familiar theme was the story of the charming little orphan girl, raised in a barren orphanage by a severe matron, who was discovered by a loving (and usually wealthy) family. The family would, of course, surmount all obstacles, adopt her, and take her home to live happily ever after.
Perhaps many readers tearfully enjoy this genre of literature because it answers to a deep longing in our hearts to be "claimed" by a loving, satisfying person. We fear nothing more than that we shall be passed by when the human race chooses its friends. To be "orphaned" can mean so much more than to be without living biological parents. Our neighborhoods are filled with emotional orphans--the neglected, the unclaimed, the inconsequential residue of a busy society.
Those with spiritual eyesight will quickly recognize that there is no more traumatic condition than to be without a spiritual Father. The vast ugliness of the whole human condition reveals that being spiritual orphans is far more than just an emotional cloud. It is an actual cause of real woe and destruction.
So Paul says that when the Spirit goes to work He gets right down inside the deepest part of our minds and prompts us to turn toward God and to speak to Him as we now see Him. And we call Him "Daddy!"--probably the best modern idiom for that ancient Aramaic word abba. It is a specially chosen word, conveying the confidence of a warm, secure sense of belonging. It is the word Jesus used when talking to His Father during prayer. (See Mark 14:36.)
When God solves the sin problem in our lives, He gets to the root of the matter. He claims us; He adopts us; He sends His Spirit to tell us "that we are children of God, and if children, then heirs, heirs of God and fellow heirs with Christ" (Rom. 8:16, 17, R.S.V.).
And this, good friends, is not a piece of literary fiction!