Source: gotquestions.org

"The first problem that comes up with this question is one of semantics. For example, many prefer "sin nature," others prefer "sinful nature," and still others prefer the ambiguous "flesh." Whatever the specific names used for the warring parties, what is relevant is that an ongoing battle rages within the Christian.

The second problem is the actual definition of "nature." How this significant word is defined determines how one sees the distinction between the “old man” and the “new man” and its relevant outworking in the life of the Christian. One way to view "nature" is to understand it as a "capacity" within a believer. Thus, the old man is interpreted as the former way of life, that of an unbeliever. In this sense, the Christian has two competing capacities within him—the old capacity to sin and the new capacity to resist sinning. The unbeliever has no such competition within; he does not have the capacity for godliness because he has only the sin nature. That’s not to say he cannot do “good works,” but his motivation for those works is always tainted by his sinfulness. In addition, he cannot resist sinning because he doesn’t have the capacity to not sin.

The believer, on the other hand, has the capacity for godliness because the Spirit of God lives within him or her. He still has the capacity for sin as well, but he now has the ability to resist sin and, more importantly, the desire to resist and to live godly. When Christ was crucified, the old man was crucified with Him, resulting in the Christian's no longer being a slave to sin (Romans 6:6). We “have been set free from sin and have become slaves to righteousness” (Romans 6:18).

At the moment of conversion, the Christian receives a new nature. It is instantaneous. Sanctification, on the other hand, is the process by which God develops our new nature, enabling us to grow into more holiness through time. This is a continuous process with many victories and defeats as the new nature battles with the “tent” in which it resides—the old man, old nature, flesh.

In Romans 7, Paul explains the battle that rages continually in even the most spiritually mature people. He laments that he does what he doesn’t want to do and, in fact, does the evil he detests. He says that is the result of “sin living in me” (Romans 7:20). He delights in God’s law according to his “inner being,” but he sees another law at work in “the members of my body, waging war against the law of my mind and making me a prisoner of the law of sin at work within my members” (v. 23). Here is the classic example of the two entities, whatever terms they may carry. The point is that the battle is real, and it is one Christians will wage throughout their lives.

This is why believers are encouraged to put to death the deeds of the body (Romans 8:13), to put to death that which makes a Christian sin (Colossians 3:5), and to put aside other sins such as anger, wrath, malice, etc. (Colossians 3:8). All this to say that the Christian has just one true nature, but that nature needs continual renewing (Colossians 3:10). This renewing, of course, is a lifetime process for the Christian. Even though the battle for sin is constant, we are no longer under the control of sin (Romans 6:6). The believer is truly a "new creation" in Christ (2 Corinthians 5:17), and it is Christ who will ultimately “rescue [us] from this body of death. Thanks be to God—through Jesus Christ our Lord! (Romans 7:24-25)."

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Oracio

This is a link to an article on the subject that I think gives it justice and clear much of the confusion associated with this topic.

http://www.stopsinning.net/Romans_7.htm

and this link shows how the first church understood Romans 7.

http://www.stopsinning.net/romans7H.htm

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Fifi

I think this issue clears up if you step back from talking about "natures". A clearer question might be, does a Christian struggle with temptation and sin?

The Bible certainly seems to indicate that, yes, a Christian does continue to struggle and fight against these things. If they did not, there would be no need for the numerous exhortations to fight the good fight, stand firm, endure, put on the armor of God, renew your mind, etc.

Praise the Lord that the Holy Spirit is working in us to will and do of his good pleasure, conforming us to the image of Christ.

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Taylor Otwell

Oracio

The question is, I think, a good one. I have considered the question as well and can give you my perspective for what it is worth.

The concept of a "nature" must be defined or we all simply talk past one another. When we say it is the nature of a dog to do the things dogs do we are really saying that the dog has no choice in the matter. It does dog things because it is a dog. It cannot change its actions. Webster puts it this way :1a : the inherent character or basic constitution of a person or thing : essence
It seems the word's origin is from the concept of birth (natal or nativity are related) and in that sense I guess we might say that we are born into sin, however the question is not whether we are born into sin but rather whether sin is our nature meaning we cannot help but sin. I do not believe that we are born with a sin nature nor that we can have a duality of nature. Please allow me to explain what is involved in my making that statement.

There are a limited number of scriptures that are used to teach that man either has a sin nature until he is born again and then has a righteous nature, or that man has a duality of nature after being born again. I would like to comment on each one.

One of these is Romans 7 and I have often heard it described as the white dog / black dog paradigm. Many believe that Paul is talking about a struggle that happens in a Christian between the flesh and the spirit. The problem with this interpretation is that the context of the chapter does not allow that interpretation. Paul has been talking for the entirety of the letter about the law and grace. He makes the point very clearly that he was alive without the law once but when the law came sin revived and he died. He is describing the wretchedness that resulted from knowing the law of God and trying to attain unto righteousness by keeping the law. Taken in context that chapter is not even hinting at a duality of natures. It is talking about a different problem entirely.

Another is Eph. 2:3. Among whom also we all had our conversation in times past in the lusts of our flesh, fulfilling the desires of the flesh and of the mind; and were by nature the children of wrath, even as others.
One might argue that this shows a sin nature, but I think idea comes from not reading the verse carefully. Actually it is making the point that by the nature of our sinful or fallen state we deserve the wrath of God. We might say, "by nature of the fact that we were sinners we deserved to be damned." And, if this were the case then we have a problem of lost individuals having a "righteous nature" in Romans 2:14 For when the Gentiles, which have not the law, do by nature the things contained in the law, these, having not the law, are a law unto themselves:
If Eph. 2:3 is to be interpreted as a sin nature then the identical statement by Paul in the other direction must be consistently interpreted to mean that some lost people have a righteous nature which we know cannot be so.

Actually we are born with a spirit that is dead in sin. It is not a literal death, but a statement of ability to be in right relationship with God. Some say "dead spiritually" and while I know what they mean, it needs a little further explanation. I think Eph 2:12-15 offers a good explanation of this state:
Eph 2:12-16 That at that time ye were without Christ, being aliens from the commonwealth of Israel, and strangers from the covenants of promise, having no hope, and without God in the world: (13) But now in Christ Jesus ye who sometimes were far off are made nigh by the blood of Christ. (14) For he is our peace, who hath made both one, and hath broken down the middle wall of partition between us; (15) Having abolished in his flesh the enmity, even the law of commandments contained in ordinances; for to make in himself of twain one new man, so making peace; (16) And that he might reconcile both unto God in one body by the cross, having slain the enmity thereby:

There may be other equally as strong statements.

When we are born again we are made nigh by the blood of Jesus. We are born again in our Spirit. We become spiritually alive in Christ. Scripture says that old things are passed away and all things are become new. Not only do we now not have a sin nature (I believe we never did), but we are made righteous.

However we still live in a corrupt flesh and have unrenewed minds (the soulish realm). So we will battle the flesh. Paul tells us in Romans 6 that we must reckon ourselves dead indeed unto sin. Again Romans 6 precludes the idea of a sin nature in a christian entirely. We are dead to sin. But we will still struggle with our flesh until the day we die and God will, by His Holy Spirit, change us from glory to glory.

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Travis

Great feedback, much appreciated. I posted that short article in the OP because I thought it could serve as a good brief introduction to this topic and I thought it pointed out some good Scriptures to consider. Regarding the passage in Romans 7 I am still not completely sure which is the correct interpretation and know it's debatable among Christians.

twayneb, regarding the phrase "sinful nature" I too have questioned whether it is a correct phrase to use. I would probably prefer "fallen","corrupted","twisted" or "fleshly" nature. That said, I think sometimes we can get caught up disagreeing due to semantics, when we basically believe the same thing but use different words. But I do see how "sinful nature" can give folk the wrong idea and may help promote excuses for wrong behavior, especially among non-believers. I hear them always saying things like, "If I was born with a sinful nature I shouldn't be held responsible for the sins which spring from my nature." Of course, that excuse will not stand when we face God on Judgment Day.

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Oracio