O most surpassing loving-kindness of God! On them who revolted from Him and were in the very extreme of misery has He bestowed such a complete forgiveness of evil deeds, and so great participation of grace, as that they should even call Him Father.
Our Father, which art in heaven; and they also are a heaven who bear the image of the heavenly, in whom is God, dwelling and walking in them.
Hallowed be Thy Name. The Name of God is in its nature holy, whether we say so or not.
However, it is sometimes profaned among sinners, according to the words, Through you My Name is continually blasphemed among the Gentiles.
Therefore we pray that in us God’s Name may be hallowed – not that it comes to be holy from not being holy, but because it becomes holy in us, when we are made holy, and do things worthy of holiness.
Thy kingdom come. A pure soul can say with boldness, Thy kingdom come; for he who has heard Paul saying let not therefore sin reign in your mortal body, and has cleansed himself in deed, and thought, and word, will say to God, Thy kingdom come.
Thy will be done as in heaven so on earth. God’s divine and blessed Angels do the will of God, as David said in the Psalm, Bless the Lord, all ye Angels of His, mighty in strength, that do His pleasure.
So then in effect thou meanest this by thy prayer, “as in the Angels Thy will is done, so likewise be it done on earth in me, O Lord.”
Give us this day our substantial bread. This common bread is not substantial bread, but this Holy Bread is substantial, that is, appointed for the substance of the soul.
For this Bread goeth not into the belly and is cast out into the draught, but is distributed into thy whole system for the benefit of body and soul.
But by this day, he means, “each day,” as also Paul said, While it is called to-day.
Cyril of Jerusalem (c. 313-386): Catechetical Lectures 23, 11-15.