Death came into the world because of man's fall. This death, which is a spiritual death, a death which separates man from God, came through sin. From the time of the fall until now, there has been no change—death always comes through sin. Romans 5:12 says that "through one man sin entered into the world." Adam sinned and sin entered into the world. "And through sin, death"; this shows that the unalterable result of sin is death. "And thus death passed on to all men." For what reason? "Because all have sinned." Not only has death "passed on to all men," but according to the literal translation of this phrase, death "passed through all men." All of man's spirit, soul, and body have been permeated by death. Death is present in every part of man. Therefore, man has no alternative but to receive God's life. The way of salvation is not dependent upon man's improvement, because "death" cannot be improved. Sin must first be judged, and then there can be the freedom from death which comes through sin. This is the salvation of Jesus Christ.
According to the ordination in the Bible, the man who sins must die. Therefore, no animal or angel can be a substitute for man to bear the punishment of sin. It is man's tripartite nature that sins; therefore, the one who dies must have man's nature. Only human nature can make redemption for human nature. Since all men have sinned, no one's death is sufficient even to redeem himself from his own sin. For this reason the Lord Jesus came and took on human nature in order to bear the judgment for human nature. He had no sin, so His holy nature could, through death, redeem the sinful nature of man. He died as a substitute, bore all the punishment of sin, and gave His life a ransom for many so that all who believe in Him shall not come into condemnation (John 5:24).
When He, as the Word, became flesh, He included all flesh in Himself. As the act of the one man Adam represented the deeds of all mankind, so the work of the one man Christ also represented the work of all mankind. We must see that Christ included all mankind before we can understand what redemption is. The transgression of the one man Adam is the transgression of all mankind, past and present. This is because Adam was the head of the human race, and all men were born of him. Likewise, the righteousness accomplished by the one man Christ becomes the righteousness of all mankind, both past and present. This is because Christ is the head of the new race, and this new man is born of Christ.
An illustration of this fact is found in Hebrews 7. Here the apostle is trying to show that the priesthood of Melchisedec is greater than the priesthood of Levi. As Abraham gave to Melchisedec a tenth of all and also received the blessing from Melchisedec, so Melchisedec is greater than Levi. Why is this? "For he was still in the loins of his father when Melchisedec met him" (v. 10). We know Abraham begot Isaac, Isaac begot Jacob, and Jacob begot Levi; therefore, Levi was the great-grandson of Abraham. When Abraham offered up his tithe and received the blessing, although Levi was not yet born, nor were his father and grandfather, the Bible nevertheless reckoned the tithing of Abraham and his receiving of the blessing to be Levi's tithing and receiving of the blessing. Since Abraham is lesser than Melchisedec, then Levi also must be lesser than Melchisedec. This event helps us to understand why all were counted to have sinned when Adam sinned, and why all were counted to have been judged when Christ was judged. When Adam transgressed, all were in his loins, and when Christ was judged, the lives of all regenerated sinners were also in His loins. For this reason, when Christ was judged for man's sin, all those who believe in Him were also reckoned to have been judged, and all those who believe in Him will not be judged anymore.