When all things are subjected to him, then the Son himself will also be subjected to him who put all things in subjection under him, that God may be all in all (1 Corinthians 15:28).
Paul plainly speaks of the nonexistence (anuparktos) of evil by stating that God is in all things and present to each one of them.
It is clear that God will truly be in all things when no evil will be found.
It is not proper for God to be present in evil; thus, he will not be in everything as long as some evil remains.
If it compels us to truly believe that God is in everything, then evil cannot be seen as existing along with faith; for God cannot be present in evil.
However, for God to be present in all things, Paul shows that he, the hope of our life, is simple and uniform. No longer can our new existence be now compared to the many and varied examples of this present life.
Paul shows, by the words quoted above, that God becomes all things for us. He appears as the necessities of our present life, or as examples for partaking in the divinity.
Thus, for God to be our food, it is proper to understand him as being eaten; the same applies to drink, clothing, shelter, air, location, wealth, enjoyment, beauty, health, strength, prudence, glory, blessedness and anything else judged good which our human nature needs.
Words such as these signify what is proper to God. We therefore learn by the examples mentioned above that the person in God has everything which God himself has.
To have God means nothing else than to be united with him. Unity then means to be one body with him as Paul states, for all who are joined to the one body of Christ by participation are one body with him.
When the good pervades everything, then the entirety of Christ’s body will be subjected to God’s vivifying power. Thus, the subjection of this body will be said to be the subjection of Church.
Regarding this point, Paul says to the Colossians, “Now I rejoice in my sufferings for your sake, and in my flesh I complete what is lacking in Christ’s afflictions for the sake of his body, that is, the Church of which I became a minister according to his dispensation” (Col. 1:24).
[…] To the Ephesians Paul more clearly puts this teaching when saying, “Rather, speaking the truth in love, we are to grow up in every way into him who is the head, into Christ, from whom the whole body, joined and knit together by every joint with which it is supplied, when each part is working properly, makes bodily growth and builds itself up in love” (Eph. 4:15-16).
Christ eternally builds himself up by those who join themselves to him in faith.
Gregory of Nyssa (c 335 – after 394): A Treatise on 1 Corinthians 15:28.