In truth, my brothers, great is the compassion of Our Lord. Inexpressible is the philanthropy which He has shown and does show towards us, who are ungrateful and thankless for his beneficence. For not only did He, out of His infinite goodness, raise us up who had fallen into sin, but He also delivered laws of prayer to us which direct us both towards God and benefit the human race, so that we might not fall again into the same sins on account of foolishness. For this reason, as is proper, the very beginning of the Lord's prayer elevates ur intellect towards His Father, the Creator of all the visible and invisible creation, and indicating the sonship of which Christians were deemed worthy, Calling Him "Father" grace.
For since Our Lord Jesus Christ became incarnate, He gave the power to all, as many as believed in Him to become children and sons of God through Holy Baptism, as John the Theologian says: "To them gave He power to become the sons of God, even to them that believe on His Name" (Jn 1, 12). And the Apostle Paul writes: "For ye are all the children of God by faith in Christ Jesus (Gal 3, 26:. And again: "And because ye are sons, God hath sent forth the Spirit of His Son into your hearts, crying Abba Father" (Gal 4, 6). That is to say, all faithful Orthodox Christians are children of God through faith and by the grace of Jesus Christ. And again, since you are children of God He m Who is your Father by grace, sent into your hearts The Holy Spirit of His Son, Who mystically cries out from there: "O Father, our Father."
For this reason our Lord tells us how we should pray towards our Father by grace, so that we may always keep under the grace of sonship, until the very end, that is, that we may be children of God, not only according to our baptismal rebirth but also according to our works and actions. For anyone who does not perform spiritual works worthy of the rebirth from above, but rather satanic works, such a person is not worthy to call God his Father, but he is to call the devil his father according to the saying of our Lord: "Ye are of your father the devil, and the lusts of your father ye will do" (John 8, 44). That is to say, you are born according to the evil of your father the devil, and you love to do his evil lusts.
The Lord directs us to call God "Father," on the one hand in order to assure us that we have truly been born as children of God by the rebirth of divine Baptism, and the other hand because we must also persevere the characteristics, that is the virtues of our Father. We will accomplish this by feeling constraint in a way because of the kinship with have with Him, as He Himself says: "Be ye therefore merciful as your father is also merciful" (Lk 6, 36). That is, be compassionate towards everyone, just as your Father is compassionate towards everyone.
Elder Nikodemos the Hagiorite