The Location of the Old Adamic Sin Nature
In Romans 5:12, Paul teaches that because of Adam’s act of disobedience each and every member of the human race possesses a sin nature, which through the function of human volition produces mental, verbal and overt acts of sin resulting in spiritual death and eventually, physical death and the second death for those who reject Jesus Christ as Savior.
Romans 5:12 Therefore, based on this (principle of reconciliation through One Man, Christ), just as, through one man, the sin nature entered into the human race so that spiritual death entered through this sin nature. Thus, in this manner, spiritual death spread to each and every member of the human race without exception because each and every member of the human race sinned (the moment Adam sinned). (Lecturer’s translation)
Romans 6:6 teaches us that the sin nature resides in the genetic structure of the human body.
Romans 6:6 Knowing this, that our old self was crucified with Him, in order that our body of sin might be done away with, so that we would no longer be slaves to sin. (NASB95)
“Our body of sin” is composed of the articular nominative neuter singular form of the noun soma, “our body” and the articular genitive feminine singular form of the noun hamartia, “of sin.”
The noun soma is a reference to the human body and the noun hamartia is not in the plural but rather in the singular and is articular indicating the sin nature is in view rather than personal sins or in other words, the word in the singular emphasizes sin as an entity and not sins in general.
The noun refers to the inherent propensity in mankind to commit mental, verbal and overt acts of sin.
The articular construction also emphasizes that Paul is speaking of sin as an entity emphasizing the underlying root cause of personal sins or the principle of sin.
The noun soma is modified by the articular genitive form of the noun hamartia, “sin,” which functions as an “attributive genitive” meaning that it specifies an attribute or an innate quality of the head noun, which is soma, “body.”
This type of genitive expresses quality like an adjective but with more sharpness and distinctness and thus, it emphasizes the “sinfulness” of the human body or in other words, that it is “inherently sinful” because it is corrupted by the sin nature, which resides in its genetic structure.
This would agree with what we see in our own bodies, which deteriorate with age and eventually cease to function and decompose and this is further indication that the sin nature resides in the genetic structure of the physical body.
The fact that the sin nature resides in the genetic structure of the physical body is why the justified sinner needs a resurrection body to replace his sinful body.
This is one of the reasons why Christ had to die physically and rise from the dead in a resurrection body because the sin nature resides in the human body.
Therefore, the human body is inherently sinful, which is the result of the curse that the Lord put on Adam and his posterity (See Genesis 3:18-19).
Douglas Moo and others disagree with this interpretation, he writes, “The ‘body’ to which Paul refers is naturally often understood to refer to the physical body. If so, the qualification ‘of sin’ would not mean that the body is inherently sinful (a Greek notion rejected by the Bible) but that the body is particularly susceptible to and easily dominated by, sin…There is little evidence that Paul conceived of the physical body as the source or reigning seat of sin. However, we should not go so far as to say simply that ‘body of sin’ means ‘man in his fallenness.’ Paul chooses soma to connote the person as the instrument of contact with the world, a choice especially appropriate in a context that speaks of crucifixion. It is that ‘aspect’ of the person which ‘acts’ in the world and which can be directed by something else: either by that person’s new, ‘higher nature’ or by ‘sin.’ Here, then, Paul wants to say that our capacities to interact with the world around have been rescued from the domination of sin.”
Some like Dodd define soma in Romans 6:6 as “the self as the organization of the sinful impulses inherent in the flesh.”
Murray, Lloyd Jones and others contend that it means that the body is dominated by sin. The body is sin’s body; it belongs to sin; sin has made it its own.
Mounce contends that the expression to soma tes hamartias, “the body of sin” refers “not to the physical body as inherently sinful but to the whole person under the control of sin.”
J.R.W. Stott interprets as “our fallen, self-centered nature.”
Morris contends that the expression “body of sin” in Romans 6:6 refers to the human body, which so easily responds to sinful impulses.
As we can see from Moo’s statement, in order for him to come to his interpretation of this expression “body of sin” he must interpret soma, “body” as being “the person as the instrument of contact with the world.”
If he doesn’t then as he even noted, then this expression means that the body is inherently sinful.
The problem with Moo’s interpretation is that soma is never used this way by the apostle in all of his writings.
In the writings of the Paul, the noun soma refers to the following: (1) The human body whether the body of mortals or Christ’s human body (Romans 1:24; 4:19; 6:6, 12; 7:24; 8:10, 11, 13, 24; 12:1; 1 Corinthians 5:3; 6:13, 15, 18, 19, 20; 7:4, 34; 9:27; 12:14, 15, 16, 17, 18; 13:3; 15:35, 40, 44; 2 Corinthians 4:10; 5:6, 8, 10; 12:2; Galatians 6:17; Ephesians 5:28; Philippians 3:21; Colossians 2:11, 23; 1 Thessalonians 5:23; Hebrews 10:5, 10, 22) (2) Figuratively for the body of Christ (Romans 12:4, 5; 1 Corinthians 10:16, 17; 12:12, 13, 20, 22, 23, 24, 25, 27; Ephesians 1:23; 2:16; 4:4, 12, 16; 5:23, 30; Colossians 1:22, 24; 2:17, 19; 3:15; Hebrews 13:3 (3) Figuratively for the Person of Christ in the Lord’s Supper (1 Corinthians 11:24, 27, 29) (4) Resurrection body of the believer (1 Corinthians 15:37, 38, 44) (5) Moon, stars and planets (1 Corinthians 15:40). (6) Bodies of animals (Hebrews 13:11).
Furthermore, up to this point in the book of Romans, soma has always been used with reference to the human body by Paul with no reference whatsoever that it denotes the person as the instrument of contact with the world (cf. Rom. 1:24; 4:19).
Also, the noun soma is used in Romans 6:12, 7:4, 24, 8:10, 11, 13 and 23 and in every instance it refers to the human body and not the person as the instrument of contact with the world.
Notice that Paul calls the human body, the “body of this death” in Romans 7:24 meaning that the sin nature is the reason why human beings are born spiritually dead and eventually die physically and in Romans 8:10 he says that the “body is dead” because of the sin nature.
Romans 8:10 If Christ is in you, though the body is dead because of sin, yet the spirit is alive because of righteousness. (NASB95)
Paul not only teaches that the sin nature resides in the genetic structure of the human body but also the Holy Spirit indwells the believer’s body and will raise the believer’s body at the resurrection (cf. Rom. 8:11, 13, 23).
Although an excellent and able expositor of the Scriptures, Moo’s exegesis in this particular instance is strained to say the least.
It seems that maybe there were some preconceived notions as to what the body of sin is, rather than letting the text speaks for itself.
The body is inherently sinful.
As we noted earlier, the fact that the sin nature resides in the human body is further indicated in that Jesus Christ’s human body was not the result of the sexual union between Mary and Joseph but rather the result of the Holy Spirit impregnating Mary (Luke 1:35; cf. Hebrews 10:5-7).
He could not have a human body that was the result of human copulation because the sin nature is passed down in this manner and resides in the body.
This is significant in that it makes clear that Jesus Christ did not have the principle of the sin nature residing in Him since the Holy Spirit impregnated Mary because He did not have a human father who could pass down the sin nature in sex.
This makes clear that our Lord was not under the headship of Adam like the rest of the human race, which is the result of physical birth.
Jesus Christ did not have a sin nature because He did not receive a human body as a result of human copulation.
Now, because He did not have a human father and that His human body did not have a sin nature residing in it, it is then clear that the rest of the human race are sinners due to the fact that they possess a sin nature that resides in their physical bodies since it is passed down through copulation.
The human body of Adam became corrupted as a result of his disobedience, which he passed down to his posterity.
Also, in Romans 6:6, the noun hamartia could also be interpreted as a “genitive of production,” which takes place when the genitive substantive “produces” the noun to which it stands related.
Therefore, we could translate the expression to soma tes hamartias, “the body, which produces sin.”
Either way you slice it, the text makes clear that the sin nature is resident in the physical body, thus making the human body inherently sinful.
Genesis 3:18-19 teaches that the fall of Adam not only affected his fellowship with God but also it effected his environment and his physical body!
The physical body of human beings eventually ceases to function and decompose into the dust of ground because it is inherently sinful because of the curse the Lord put on Adam and his posterity.
Therefore, in Romans 6:6, the noun soma is obviously a reference to the human body.
 The Epistle to the Romans, pages 375-376; William B. Eerdmans Publishing Company; Grand Rapids, Michigan/Cambridge, U.K.  Cited by Morris, The Epistle to the Romans; page 251; W. B. Eerdmans; Inter-Varsity Press  The New American Commentary, volume 27, Romans, page 151; Broadman and Holman Publishers  Romans [Downers Grove: InterVarsity, 1994], page 175