Hence the question was not, “Is there a God?” It was “Granted that there is a God, what is this God like?” 

To that question Christ’s answer was one constantly reiterated word—“Father.” Within the short compass of our Gospels that name occurs more than 150 times. It is there in the first recorded boyhood utterance of Jesus—“Wist ye not that I must be about my Father’s business?” (Luke 2:49). It is there in his last dying cry—“Father, into thy hands I commend my spirit” (Luke 23:46). Christendom, with the Gospels in its hands, has inevitably fixed on this as the supreme name of God forever.

2) The Original Element in Jesus’ Teaching. It would not, of course, be true to suppose that Jesus was the first to call God Father. Dimly and gropingly the men of the Old Testament had been feeling after this great thought on which Christ set his seal. To begin with they conceived of God’s fatherhood almost solely in the national sphere. He was the Father of the chosen people. “Thus saith the Lord,” said Moses to Pharaoh, “Israel is my son, even my firstborn” (Exodus 4:22). That was a national fatherhood. But already in the Old Testament you can see men’s thoughts moving out to something deeper and more personal, especially in some of the psalms, as, for example when God is called the “father of the fatherless” (Psalm 68:5), or in that word of wonderful compassion and beauty—“Like as a father pitieth his children, so the Lord pitieth them that fear him” (Psalm 103:13). We cannot say that Jesus was the first to call God Father.

In what respects, then, was his teaching here original and new? In two respects. 

He took this thought that had been a stray guest, hovering uncertainly on the dim borderland and circumference of men’s minds, and made it the center of everything. Before Jesus many good people had thought of God’s relationship to men mainly in terms of a potter and his clay, or a creator and his creatures, or a dictator and his subjects. But to Jesus all these conceptions were dim half-lights, hiding as much as they revealed. The likest thing on earth to God’s relationship to men, said Jesus, was the family relationship, the life of a father and his children. Now that new emphasis of Jesus, that centralizing of this conception, was something unheard of and revolutionary; and it changed the whole face of religion. 

The other respect in which Jesus’ thought of God as Father was completely original was the new depth and content he put into the word. For not only did he make the word central; he enriched it beyond recognition. And he did that, not so much by anything he said, as by the way he lived. Jesus alone in history has lived out consistently and unbrokenly and shiningly and triumphantly the kind of life that a vital sense of the divine fatherhood should imply. Here in this absolutely filial life of Christ, this perfect sonship of the Master, all the tenderness and strength and serenity and amazing everlasting dependableness of the Father-God are mirrored. So Jesus gave the word “Father” a depth of which men had never dreamed. 

The Life and Teaching of Jesus Christ - James Stewart