For we are members of his body, of his flesh, and of his bones. First, this is no exaggeration, but the simple truth. Secondly, he does not simply mean that Christ is a partaker of our nature, but expresses something higher (kai emphatikoteron) and more emphatic.

For we are members of his body - Of the body of Christ; see 1-Corinthians 11:3, note; 1-Corinthians 12:27, note; John 15:1-6, notes, and Ephesians 1:23, note. The idea here is, that there is a close and intimate union between the Christian and the Saviour - a union so intimate that they may be spoken of as "one".
Of his flesh, and of his bones - There is an allusion here evidently to the language which Adam used respecting Eve. "This is now bone of my bones, and flesh of my flesh;" Genesis 2:23. It is language which is employed to denote the closeness of the marriage relation, and which Paul applies to the connection between Christ and his people. Of course, it cannot be understood "literally." It is not true literally that our bones are a part of the bones of Christ, or our flesh of his flesh; nor should language ever be used that would imply a miraculous union. It is not a physical union, but a union of attachment; of feeling; of love. If we avoid the notion of a "physical" union, however, it is scarcely possible to use too strong language in describing the union of believers with the Lord Jesus. The Scriptures make use of language which is stronger than that employed to describe any other connection; and there is no union of affection so powerful as that which binds the Christian to the Saviour. So strong is it, that he is willing for it to forsake father, mother, and home; to leave his country, and to abandon his possessions; to go to distant lands and dwell among barbarians to make the Redeemer known; or to go to the cross or the stake from simple love to the Saviour. Account for it as people may, there has been manifested on earth nowhere else so strong an attachment as that which binds the Christian to the cross. It is stronger love that that which a man has for his own flesh and bones; for it makes him willing that his flesh should be consumed by fire, or his bones broken on the wheel rather than deny him. Can the infidel account for this strength of attachment on any other principle than that it has a divine origin?
(See the supplementary note, Romans 8:10, on the union between Christ and his people, in which it is shown that a mere union of feeling and love is far beneath the truth.)

We are members of his body - He has partaken of our nature, as we have partaken of the nature of Adam. And as he is the head of the Church and the Savior of this body; so we, being members of the Church, are members of his mystical body. That is, we are united to him by one Spirit in the closest intimacy, even similar to that which the members have with the body.

For we are members of his body, (q) of his flesh, and of his bones.
(q) He alludes to the making of the woman, which signifies our union with Christ, which is accomplished by faith, but is signified in the ordinance of the Lord's supper.

For we are members of his body,.... Not of his natural body, for this would make Christ's human nature monstrous; Christ, as man, is of our flesh and of our bones, or a partaker of the same flesh and blood with us; or otherwise, his incarnation would have been of no service to us; and had our human nature been from Christ, it would not have been corrupted; but our bodies, flesh, and bones, are from the first, and not the second Adam, and so corrupt and sinful; Christ indeed, as God, is the former of all human nature, and, as man, was set up in God's thoughts as the pattern of it; but the apostle is here speaking of the saints, not as men, but as Christians, as new creatures in Christ; and of what is peculiar to them; and therefore this must be understood of Christ's mystical body the church; which is his by the Father's gift, and his own purchase; and of which he is the head, and which is united to him; now of this saints are members; see Romans 12:5.
Of his flesh and of his bones: for so the church may be called, his own flesh, his flesh and bones, on account of the marriage relation she stands in to him, and that spiritual union there is between them, which these phrases are expressive of; and which the near relation of man and wife is an emblem of; these words are wanting in the Alexandrian copy, and in the Ethiopic version.

For--Greek, "Because" (1-Corinthians 6:15). Christ nourisheth and cherisheth the Church as being of one flesh with Him. Translate, "Because we are members of His body (His literal body), being OF His flesh and of His bones" [ALFORD] (Genesis 2:23-24). The Greek expresses, "Being formed out of" or "of the substance of His flesh." Adam's deep sleep, wherein Eve was formed from out of his opened side, is an emblem of Christ's death, which was the birth of the Spouse, the Church. John 12:24; John 19:34-35, to which Ephesians 5:25-27 allude, as implying atonement by His blood, and sanctification by the "water," answering to that which flowed from His side (compare also John 7:38-39; 1-Corinthians 6:11). As Adam gave Eve a new name, Hebrew, "Isha," "woman," formed from his own rib, Ish, "man," signifying her formation from him, so Christ, Revelation 2:17; Revelation 3:12. Genesis 2:21, Genesis 2:23-24 puts the bones first because the reference there is to the natural structure. But Paul is referring to the flesh of Christ. It is not our bones and flesh, but "we" that are spiritually propagated (in our soul and spirit now, and in the body hereafter, regenerated) from the manhood of Christ which has flesh and bones. We are members of His glorified body (John 6:53). The two oldest existing manuscripts, and Coptic or Memphitic version, omit "of His flesh and of His bones"; the words may have crept into the text through the Margin from Genesis 2:23, Septuagint. However, IRENÆUS, 294, and the old Latin and Vulgate versions, with some good old manuscripts, have them.

For we - The reason why Christ nourishes and cherishes the church is, that close connexion between them which is here expressed in the words of Moses, originally spoken concerning Eve. Are members - Are as intimately united to Christ, in a spiritual sense, as if we were literally "flesh of his flesh, and bone of his bone."