What is the Sin Nature?
When Adam sinned, his nature became bent towards doing wrong because in sinning he not only determined to reject God’s word, but also separated himself from God. After this happened, all of the offspring from Adam and Eve were born with his fallen image and likeness. As a result, we are all born separated from God in our spirit with a nature that wants to do wrong; even though we have a conscience which knows what is beneficial (good) from what causes calamity (evil).
Wrong does not just mean wicked or evil, although both of these terms can be included in doing wrong. Most of the things we seek to do that are wrong are a result of us rejecting God’s way and seeking to do it our own. Such as, we want to please God through our own efforts (works) rather than living out from faith through grace. Both actually produce works. Faith without works is dead – how can you say you have faith if your actions never show it? One manifests works to please God, the other displays works because in Christ we are already pleasing to Him. Israel rejected the righteousness of God in Christ because they sought to make their own righteousness through works.
The Sin Nature is terminology that is used to describe our bent nature that we received from Adam. Scripture does not use this specific term, but rather refers to it as sin or the flesh. However, it does specifically describe a part of us that seeks to do those things that we know are not right and how to overcome it, which is not referring to sinning – the act of lawlessness. Therefore, the term Sin Nature is used to help us better distinguish when our nature is being addressed rather than the act of sinning.
In Romans 11:14-21 Paul gives detail on the struggle we face every day with the sin nature.
For we intuitively know that the law is logical, but I, on my part, am fleshly, having been sold under the sin nature. For that which I work out, I do not experientially know, for that which I do not desirously will, this I practice, but that which I am indifferent to, this I do. But since that which I do not desirously will, this I do, I together say with the law that the law is good in appearance. But now I, on my part, no longer work it out for myself, but the dwelling in me sin nature. For I intuitively know that dwelling in me, that is in my flesh, is no good. For the desirous will is present with me, but the working out of the good in appearance, it is not found.For not that which I desirously will, to do good, but that lacking in character which I do not desirously will, this I practice. But since that which I do not desirously will, I, on my part, this I do, it is no longer I working it out, but the dwelling in me sin nature. Then I find the principle to desirous will in me to do the good in appearance, that in me the lacking in character is present.
The flesh is where the sin nature resides so when someone is called carnal (fleshly) they are manifesting the desires of the flesh, which are contrary to the desires from a spirit that is connected to God. This is the struggle Paul is referring to in Romans. He wants to do good, but every time he tries there is another part in him that wants to do wrong. The result is he often does what is wrong, even though he starts off with no intention of do it.
All who are not in the Christ are slaves to their sin nature.