N.T. Wright on "Our Father"

The first occurrence in the Hebrew Bible of the idea of God as Father comes when Moses marches in boldly to stand before Pharaoh, and says: Thus says YHWH: Israel is my son, my firstborn; let my people go, that they may serve me (Exodus 4:22-23). For Israel to call God 'Father', then, was to hold on to the hope of liberty. The slaves were called to be sons.

When Jesus tells his disciples to call God 'Father', then, those with ears to hear will understand. He wants us to get ready for the new Exodus. We are going to be free at last. This is the Advent hope, the hope of the coming of the Kingdom of God. The tyrant's grip is going to be broken, and we shall be free:

I see my light come shining,
From the west down to the east.
Any day now - any day now -
I shall be released

N.T. Wright, The Lord and His Prayer