“For ye have not received the spirit of bondage again to fear; but ye have received the Spirit of adoption, whereby we cry, Abba, Father. The Spirit [Himself] beareth witness with our spirit, that we are the children of God:” (Romans 8:15-16)
Here we have before us another wonderful function of the Holy Spirit in the life of the believer. He places everyone who trusts in Jesus Christ into a new position with the Most High God, adopting us into the family of the Father through the new birth that occurs at the point of Salvation.
There is an intended distinction between the “sons of God” position of Romans 8:14 and the “children of God” relationship of verse 16. Our “sonship” speaks of a legal position, a condition of contract wherein the benefits and inheritance of being part of the household of the Father are in view. Verse 17 will go on to describe the individual Christian as a “joint-heir” with Christ, a partaker of a particular reign and glory that the Father will bestow upon His sons and daughters in the Age to come (cf. Rev. 22:4-5).
Yet even in the midst of describing our “legal” position as adopted sons and daughters of the Father, Paul employs the word Abba to define Who God is to us. We have been adopted, yes, but our relationship is never to be interpreted as a cold and distant one. God is our Abba, our dear Father, our Daddy; He is our loving Parent, intimate and even closer to His children than any flesh and blood father could be.
Referring elsewhere to our adoption as sons of God through the Holy Spirit, Paul uses Abba again in Galatians 4:5. Adoption can often carry with it the implication of a “second-class” relationship inferior to that of a natural-born child. However it seems that the Spirit of God, in giving the inspiration for the writing of His Holy Word, made sure that we understand that no such lesser relationship to our Heavenly Father is ever suggested. Wherever the Word speaks of our adoption, it invites us to use the same term of affection and closeness that the Lord Jesus used Himself when addressing the Father (Mark 14:36).
To Abba goes all glory. In service to Him,