“For what the law could not do in that it was weak through the flesh, God did by sending His own Son in the likeness of sinful flesh, on account of sin: He condemned sin in the flesh” (Rom. 8:3)
There is a common idea that this means that Christ simulated sinful flesh; that He did not take upon Himself actual sinful flesh, but only what appeared to be such. But the Scriptures do not teach such a thing. “In all things He had to be made like His brethren, that He might be a merciful and faithful High Priest in all things pertaining to God, to make propitiation for the sins of the people” (Heb. 2:17). He was “born of a woman, born under the law…that He might redeem those who were under the law” (Gal. 4:4,5).
He took the same flesh that all have who are born of woman. A parallel text to Romans 8:3,4 is found in 2 Cor. 5:21. The former says that Christ was sent “in the likeness of sinful flesh…that the righteous requirement of the law might be fulfilled in us.” The latter says that God “made Him…to be sin for us,” although He knew no sin, “that we might become the righteousness of God in Him.”
All the comfort that we can get from Christ lies in the knowledge that He was made in all things as we are. Otherwise we should hesitate to tell Him of our weaknesses and failures. The priest who makes sacrifices for sins must be one who “can have compassion on those who are ignorant and going astray, since he himself is also beset by weakness” (Heb. 5:2).
This applies perfectly to Christ; “for we do not have a High Priest who cannot sympathize with our weaknesses, but was in all points tempted as we are, yet without sin” (Heb. 4:15). This is why we may come boldly to the throne of grace for mercy. So perfectly has Christ identified Himself with us, that He even now feels our sufferings.
Waggoner, Waggoner on Romans, pp. 128,129