Juan asked me a great question in email; “What is the Old Nature and New Nature?”
The Bible calls the ‘old nature’ sin or the flesh. The apostle Paul says that the law of sin dwells in our body (Romans 7:23) and he goes further and encourages us not to let sin control us in our mortal body (Romans 6:12) suggesting that sin is always present in us.
Christians are capable of both righteousness and sin because Christians have two natures from which to draw their actions and reactions from. In this sense, all human beings have only one nature that includes one moral faculty that is capable of both good and evil. Yet in addition to the orientation around the interests of one’s self that all humans possess, Christians are given an additional orientation around the interests of God. The new orientation, being born again in Christ, inclines us toward good and thus wages war with our original orientation sin, which inclines us toward evil (Galatians 5:16–17; Romans 7:15–25; James 4:1–3; 1 Peter 2:11).
Now it isn’t as though Christians started out with three-fourths of the original nature and one-fourth of the new and then now Christians must work to decrease the old nature and increase their new nature. Christians’ old nature is still there in each of them and is in its full strength and ugliness — Christians however are no longer slaves to the old nature. Christians can and must choose daily which nature they are going to “clothe” themselves with or “put on” (Romans 13:14; Ephesians 4:22–24; Colossians 3:1–14). A Christian’s sanctification consists of increasingly learning to live according to the new capacity Christians have to “put on” their new nature, which is accomplished as the Word of God is applied to every area of one’s life (Psalms 119:11, 105; James 1:22–27; Hebrews 4:2; 5:12–14; 1 John 2:4–5).
Paul calls the sin nature the “flesh.” It is human nature apart from the redeeming influence of the Spirit of God, and thus Paul can say, “I know that nothing good lives in me, that is, in my flesh” (Rom. 7:19). Since sin remains “right there with” every believer (Romans 7:21), you and I must make a conscious choice to walk according to the new nature (Romans 8:13; Galatians 5:24; Colossians 3:5).
1 John 1:8 specifically states, “If we say that we have no sin, we are deceiving ourselves and the truth is not in us.” Note that John speaks of having sin, not committing sin. To have sin it means that you and I possess a disposition toward evil that must be counteracted by the new disposition toward good we received in Christ.
At this point, I’m going to move to talking about temptation because it kind of goes hand in hand with old nature vs. new nature. Being tempted is not a sin. Giving into temptation is a sin. Our old nature would easily give into temptation whereas our new nature helps us to not fall into temptation.
Everyone here on earth has been tempted and will be tempted at some point in their life. Even Christ Jesus himself was tempted. Matthew 4: 1
So basically, there is no avoiding all temptation as everyone will at some time in their life be tempted.
Now with that said however, there are things we can do to help avoid being tempted. We need to remember what Jesus said in Mark 14: 38; “Watch and pray so that you will not fall into temptation. The spirit is willing, but the body is weak.”
With our body being weak, you and I need to not put ourselves into places that we know that will have things there which will entice us and lead us astray from Christ Jesus’ teachings. For example, you and I should not go to places where we know we’d get into trouble of some sort. For you or me to go to a place like that, we would be just asking for trouble and be most likely following our old nature.
We need to remember; “No temptation has seized you except what is common to man. And God is faithful; he will not let you be tempted beyond what you can bear. But when you are tempted, he will also provide a way out so that you can stand up under it.” 1 Corinthians 10: 13 This “way out” is highlighted by our new nature in Christ so that we can easily find the “way out.”
God has promised to us that when we do find ourselves in a tempting situation, you and I always have the means to escape from it; we can always say no, leave, run away if needed, etc. which is our new nature in Christ leading us away from sin. As always, it is our choice to which nature (old or new) we follow. It’s always best for us to follow our new nature as God always knows and wants what is best for us.