15 For you did not receive the spirit of bondage again to fear, but you received the Spirit of adoption by whom we cry out, “Abba, Father.”
by whom [the Holy Spirit] we cry out,
It is the Spirit who enables us to fervently pray. Christians can approach God on personal terms; we can talk to the Father as a son would. The words “cry out” indicate intensity.
“Abba [Aramaic for father], Father [Greek].”
The word “Abba” is Aramaic and the word “Father” is Greek. Both words mean the same thing. These are terms of personal relationship. They are family words. By using both terms Paul strengthens the cry to God the Father. This is recognition by the believer that he or she has privilege with God. God is personal, not some distant being who does not relate to His creatures.
The Holy Spirit gives the believer special enablement to pray on the basis of our sonship.
We take God at His word that we are His children. We are dearer to God than we realize. God is open to hear our cry. He is open because of our status as sons.
Ga 4:6, And because you are sons, God has sent forth the Spirit of His Son into your hearts, crying out, “Abba, Father!”