“God is, for Jesus, above all ‘Father,’ which is both a name and a metaphor. This is striking. The chief theme in the tradition is the kingdom of God. We might expect, then, that its primary image of the divinity would be that of a king, especially as the image of God seated on a throne recurs so often in the Hebrew Bible and Judaism. References to God as king, however, appear only occasionally in the sources for Jesus, who far more frequently speaks of God as Father.
Partial explanation may lie in this, that Jesus and his hearers had no access to a royal court; that is, unlike weddings and fathers, lilies and the birds of the air, their firsthand knowledge of kings was nil. No less important than this social fact, however, is a theological fact: Jesus seems to have conceptualized the divine rule in contrast to the tyrannical rule of the stereotypical monarch.
God does not, in the Jesus tradition, exploit human beings but relates to them in ways analogous to how a loving parent deals with a child. Instead of repressive dominion, there is care and nurture…The politics of heaven are not the politics of earth.
In line with this is Matt. 17:24-27, where Jesus, in discussing the temple tax, asks ‘From whom do kings of the earth take toll or tribute? From their children or from others?’ Although the paragraph assumes that God is a king, Peter’s answer—‘from others’—and Jesus’ response—‘then the sons are free’—indicate that God relates to the disciples not as a potentate to exploited subjects but as a father to privileged members of his family.
So although a king, God is even more a father, and a father in that he is profoundly kind and merciful. This is in fact the heart and soul of Jesus’ theology.” (Dale C. Allison, The Historical Christ and the Theological Jesus, pp. 105-06)