"The title 'our Father' teaches us with what faith and confidence we are to pray to God. We are not to pray in proud and Pharisaic presumption based on our own justice or worthiness, or on the works and merits either of ourselves or others. We are to pray with the humble acknowledgement and confession of our own unworthiness. We are to pray with the merits and intercession of the only Son of God, our Mediator, through whom the Father has adopted us to be sons and heirs (Eph. 1:5).
Likewise, the fullness of this title 'Father' reminds us of a very sweet consolation. We have 'a merciful and faithful high priest in service to God' (Heb. 2:17). 'But if anybody does sin, we have one who speaks to the Father in our defense...He is the atoning sacrifice for our sins' (1 John 2:1-2). 'He is able to save completely those who come to God through him, because he always lives to intercede for them' (Heb. 7:25, cf. Heb. 9:24). He has received gifts from kings (Ps. 68:29), and he gives the same to us (Eph. 4:11). We are not commanded to call God a lord, just, great, almighty, or terrible, but our Father. By these words those who pray are confident that they will be heard and that they will obtain their requests. 'Let us then approach the throne of grace with confidence, so that we may receive mercy and find grace to help us in our time of need' (Heb. 4:16)... The title 'Father' gives us confidence. As Christ himself declares in John 16:23, our prayers are neither grievous nor ungrateful to God. The Father so loves us that he is delighted with this our duty. When we come to him with our prayers, his fatherly mind is full of care for our necessities (Matt 6:32). Of his own accord he is ready and active to hear and to help us 'as a father has compassion on his children' (Ps 103:13; cf. Lk. 11:9)."