As my Adult Education group keeps going through the Our Father, accompanying the reflections of Dr. Hahn on this greatest of prayers, we come to the the second point: who art in heaven. Recall, that in merely referring God as Father, and proclaiming Him to be Our Father, we set the foundation of this prayer in the terms of relationship, specifically, familial relationship.
This relationship, though, is unlike any other relationship of which we have experience. Since we are dealing with a relationship with God, who is neither limited to time and space, the depths of that relationship are mind-boggling. When we call God 'Father', we may allow the diminished images of fatherhood we are familiar with to color, warp, if not destroy, who God as Father is. We can take all of the warped images provided in our media, a media who actively rebels against a positive description of fatherhood. WE can see the fathers in our own lives and their foibles and imperfections. We can see the priests whom we call 'father' who fail to live up to that awesome responsibility. We might even see those fathers, both paternal and religious, who were good men and tried their best. All of that said, God, our 'Father' is the perfection of fatherhood and far greater than even the greatest of our dads might be. He 'is in heaven', He is the prototype and image of what fatherhood is to be about. As He is in heaven (not to the exclusion of being among us), He is eternal in His fatherhood and it is His Fatherhood that is perfect. Like an earthly father, he creates and brings forth life. Unlike earthly fathers, whose love is imperfect or altogether gone, His love for us knows no bounds or limits. As we see in the parable of the Prodigal Son, though, the fullness of his gifts depends upon our submitting to his will and protection.
That our Father is in heaven also tells us of whose home we belong. Our eternal home lies not of this life nor existence. This passing home, though, is where we make the decision whether we truly want God as our Father. We make our choice here as to which kingdom we belong. Since God created us not be mindless robots incapable of loving Him as He loves us, he allows us to choose whether we will attach ourselves to His household. When we pray "Our Father, who art in heaven", we are at least vocally saying to whose home we wish to belong. But our commitment to God must be more than words; our lives must proclaim that we belong to the household of God. Fr Larry Richards, in his book "Be a Man", reminds us that when we call God 'our Father', we are saying to God, "Father, I am your son/your daughter." We bind ourselves to a loving Father and that which belongs to Him. Again, the ideas of relationship (especially familial relationship) are in fill play. What a tremendous act of faith and promise to relationship we make in saying just these words: Our Father who art in heaven!