John Chrysostom

"Because we are members of His body, of His flesh and of His bones." Tell me not that such and such things are so. Seest thou not that we have in our own flesh itself many defects? For one man, for instance, is lame, another has his feet distorted, another his hands withered, another some other member weak; and yet nevertheless he does not grieve at it, nor cut it off, but oftentimes prefers it even to the other. Naturally enough; for it is part of himself. …

Homily on Ephesians 20 ↗

Theophylact of Ohrid

That is, we have a great kinship with Him. For He came from our substance, just as Eve from Adam. And as there the closeness was so great, so it is with us as well. And from another perspective too, we are "of His flesh and of His bones," because just as He was born of the Spirit without conjugal union, so are we in the baptismal font; and because having received the mysteries, we are from that moment divinely re-created. In short, he says that we have the highest closeness to Him. …

Commentary on Ephesians ↗

Theodoret of Cyrus

Just as Eve was fashioned from Adam, so were we from Christ the Lord. We are buried with him in baptism. We rise with him. We eat his body and drink his blood [in the Eucharist].

Interpretation of the Epistle to the Ephesians 5.30 ↗

Thomas Aquinas

Then he indicates that a man must love his wife through an example. Thus he says, Christ also loved the Church as something of his very self because we are members of his body. "For we are members one of another" (Eph. 4:25). He mentions of his flesh on account of his sharing the same nature with us. "For a spirit hath not flesh and bones, as you see me to have" (Lk. 24:39). Or, he says this mystically so that of his flesh refers to the weak who are of the flesh, and of his bones would refer to the strong who are hard as bone.

Commentary on Ephesians ↗