“And because ye are sons, God hath sent forth the Spirit of His Son into your hearts, crying, Abba, Father” (Galatians 4:6).

Perhaps the most moving portions of Scripture are found in the record of Christ’s agony in the Garden of Gethsemane. “And He went forward a little, and fell on the ground, and prayed that, if it were possible, the hour might pass from Him. And He said, Abba, Father, all things are possible unto thee; take away this cup from me: nevertheless not what I will,
but what thou wilt” (Mark 14:35,36).
Because of Christ’s willingness to do His Father’s will, we are given the privilege of crying “Abba, Father” (Romans 8:15)—an endearing, intimate term. Jesus said, “I ascend unto my Father, and your Father; and to my God, and your God” (John 20:17). He “knoweth what things ye have need of, before ye ask Him” (Matthew 6:8).
What we can know of our Father we have learned through Jesus Christ. He is our righteous “advocate with the Father” (I John 2:1). To Philip’s request, “show us the Father,” Jesus replied, “He that hath seen me hath seen the Father” (John 14:8,9). “For as the Father hath life in Himself; so hath He given to the Son to have life in Himself” (John 5:26). And note the security which comes through God’s Fatherhood. “My Father, which gave them me, is greater than all; and no man is able to pluck them out of my Father’s hand. I and my Father are one” (John 10:29,30).
The key to our relationship with the Father is our relationship to His Son. Jesus said “He that loveth me shall be loved of my Father” (John 14:21); “if any man serve me, him will my Father honor” (John 12:26). Jesus is the vine, we are the branches, and our heavenly Father is the husbandman—glorified when we bear much fruit (John 15:1–8).

 Abba is the transliteration of the Aramaic word for father. It occurs three times in the New Testament. It is always used as a direct address to God the Father. In Mark 14:36
, Jesus uses it when He asks the Father to take away his cup. In Romans 8:15
and Galatians 4:6
, it is the cry of the Spirit of God in the believer. 
Historically, this word would be used during New Testament times by a child addressing his or her father. It would have been akin to the modern use of papa. However, the New Testament writers are careful to avoid too great a familiarity in addressing God. Instead of translating Abba, they transliterate it, so that it takes on special significance in reference to God. Then, Abba is used in conjunction with the word Father – “Abba, Father.” Father is the translation of Abba, but by putting the two together, the address to God is both personalized and kept in the proper tone of respect. The double title has both intimacy and dignity.
By His nature as the Son of God, Jesus had the right to familiarly address His Father. The occasion where we see this is in the Garden of Gethsemane when Jesus struggled with the cup He was to drink. In His human spirit, He desired the cup to be removed. Yet, in His obedience as the Son, He declared, “nevertheless not what I will, but what thou wilt” (Mark 14:36
). This incident provides a glance into the intimate communion between the Father and the Son. The Son’s faithfulness to obey the most difficult of acts, an act by which the holy Son of God became sin for mankind, was proof of the depth of His love for the Father (John 14:31
).
By his union with Jesus Christ, the believer enters into the same intimacy with the Father. Instead of the fear of bondage, the believer receives “the Spirit of adoption” (Romans 8:15
) and enters into “the adoption of sons” (Galatians 4:5
). By reason of this sonship, “God hath sent forth the Spirit of his Son into your hearts, crying, Abba, Father” (Galatians 4:6
). The legal relationship is created by adoption; the intimacy is assured by the entrance of Jesus Christ into our hearts. We then cry, “Abba, Father,” with the Spirit of the Son. As stated in 1John 1:3
, “truly our fellowship is with the Father, and with his Son Jesus Christ.”