God, the Father Almighty, has one Son naturally, and many adoptively.
Christ is the Son of God, seeing that the Father begot him of himself without any mother.
The Father has no body, nor begot he his Son in that wise which men do: but his Wisdom, with which he wrought all creatures, is his Son, who is ever of the Father and with the Father, God of God, as mighty as the Father.
We men are children of God, because he made us; and afterwards, when we were undone, he sent his own Son for our redemption.
Now are we children of God, and Christ is our brother, if we will duly obey the Father, and with all our mind worship him.
Christ is our head, and we are his limbs: he is invested with our humanity, and he has our body, which he received of the holy maiden Mary;
therefore may we manifestly cry to him, as to our brother, if we so observe our brotherhood as he has taught us; that is, that we should not allow the devil with any evil practices to seduce us from the brotherhood of Christ.
[…] The man who makes himself acceptable to God is a child of God, not naturally, but by creation and by good deserts, as Christ said in his gospel, “He who doeth the will of my Father who is in heaven, he is my brother, and my mother, and my sister.”
[…] We say, “Pater noster qui es in cœlis,” that is, “Our Father which art in heaven;” for God the Father is in heaven, and he is everywhere, as he himself said, “I fill with myself heaven and earth.”
And again, the holy gospel says thus concerning him, “Heaven is his throne, and earth is his footstool.”
We turn eastward when we pray, because from thence the heaven rises; not as though his dwelling be particularly in the east part, and that he forsakes the west or other parts, who is everywhere present, not through the space of the place, but by the presence of his majesty.
When we turn our face to the east part, where the heaven rises, which rises over all bodily things, then should our mind be thereby admonished that it turn to the highest and first nature, that is, God.
We should also know that the sinful is called earth, and the righteous is called heaven; for in righteous men is a dwelling-place of God, and the good man is a temple of the Holy Ghost.
Ælfric of Eynsham (c. 955 – c. 1010): Homily 19 (On the Lord’s Prayer), trans. Benjamin Thorpe; icon of All Saints of Britain and Ireland.