"Christ commands us to call God "our Father" . . . Granted, the Fatherhood of God will be challenging for some. Some Christians grew up with weak fathers, abusive fathers, or no father at all. We can sympathize with those for whom "Father" stirs up all sorts of bad connotations. But sympathy does not trump Scripture. We ought to interpret our experiences through God's revelation and not the other way around. So instead of running from the Fatherhood of God because we had a bad father, we ought to let God define true Fatherhood for us and grieve that fathers fell so far from the divine example. For those who hate their father, learning to love our heavenly Father can bring necessary healing and forgiveness. Embracing God as Father is part of our discipleship as Christians. We call on God as Father in our prayers to remind us that we are His children and He knows what is best for us." Kevin DeYoung. The Good News We Almost Forgot. 215-216. 

Question 120: Why did Christ command us to call God "our Father"?

Answer: At the very beginning of our prayer, Christ wants to kindle in us what is basic to our prayer - the childlike awe and trust that God through Christ has become our Father. Our fathers do not refuse us the things of this life; God our Father wil even less refuse to give us what we ask in faith. 

Question 121: Why the words "in heaven"?

Answer: Those words teach us not to think of God's heavenly majesty as something earthly, and to expect everything for body and soul from His almighty power.