We are all of one nature, because we are sons of Adam; we are all of one nature, because we are brethren of Christ. Our old nature is common to us all, and so is our new nature. And because our old nature is one and the same, therefore is it that our new nature is one and the same. Christ could not have taken the nature of every one of us, unless every one of us had the same nature already. He could not have become our brother, unless we were all brethren already; He could not have made us His brethren, unless by becoming our Brother; so that our brotherhood in the first man is the means towards our brotherhood in the second.
I do not mean to limit the benefits of Christ's atoning death, or to dare to say that it may not effect ends infinite in number and extent beyond those expressly recorded. But still so far is plain, that it is by taking our nature that He has done for us what He has done for none else; that, by taking the nature of Angels, He would not have done for us what He has done; that it is not only the humiliation of the Son of God, but His humiliation in our nature, which is our life. He might have humbled Himself in other natures besides human nature; but it was decreed that "the Word" should be "made flesh." "Forasmuch as the children are partakers of flesh and blood, He also Himself likewise took part of the same." And, as the text says, "He took not hold of Angels, but He took hold of the seed of Abraham."
And since His taking on Him our nature is a necessary condition of His imparting to us those great benefits which have accrued to us from His death, therefore, as I have said, it was necessary that we should, one and all, have the same original nature, in order to be redeemed by Him; for, in order to be redeemed, we must all have that nature which He the Redeemer took. Had our natures been different, He would have redeemed one and not another. Such a common nature we have, as being one and all children of one man, Adam; and thus the history of our fall is connected with the history of our recovery.
Christ then took our nature, when He would redeem it; He redeemed it by making it suffer in His own Person; He purified it, by making it pure in His own Person. He first sanctified it in Himself, made it righteous, made it acceptable to God, submitted it to an expiatory passion, and then He imparted it to us. He took it, consecrated it, broke it, and said, "Take, and divide it among yourselves."