Nothing that Israel was instructed to do in the Old Testament to be acceptable to God, ever destroyed the sin nature. They did not even know they had a sin nature, they knew they sinned but did not know they had a nature compelling them. Father Abraham, had great faith to do things for God, but as great as his faith was it could not rid him of the sin nature. A point should be made about nature; stability is found in a nature, because nature cannot and does not change. The sin nature is a controller and desires to totally control the individuals mind, Romans 7:17, 17 Now then it is no more I that do it, but sin that dwelleth in me. I have had Christians ask me "do you think God has turned me over to a reprobate mind" my answer is simply "no." A reprobate mind can only afflict those that have a sin nature. A reprobate mind is; the sin nature gaining control of the mind. The question will come up "why do Christians sin" again the answer is simple; because their minds were trained by the nature (sin) and against that nature they warred, even as a non believer. Very important for the believer to be renewed in mind and at best they will not live under condemnation, because you will never perfect this life. We strive to be Christlike and allow the mind of christ to freely express itself, but as long as you're in this body you will sin. The pulls of your body and areas of the mind that remain unrenewed cause the believer to fail. If you fast and walk by a refrigerator you will see how strong the body pulls can be. If you desire to quit smoking, drinking or some other body pull, you will see how the mind and body work together. It is not a spirit thing as some suppose, it is mind given to body, nothing wrong with your spirit you are one with Christ. Finding out about that and getting your mind renewed will help you live life as your Father intended you to live, which is by your new nature. We have a choice, before the cross there was no choice, they had to live with a nature they didn't even know existed. The only people that can be double minded is believers, simply because we have a choice.