If we have found the Lord, we are saved but we still have the old nature within us. There are some – and many of them are fine Christians, and fine exegetes – who have taken the more modern view that the old nature is no longer in the Christian. We do not believe that is the correct way to expound the Scripture. No, the spirit is willing, but the flesh is weak. Human nature, the old nature, is still there, and it can reassert itself if we are not watchful. The new nature is superior and strong and wonderful – the new heart and the new nature given at conversion – but the old nature, ‘residual sin’ as the Puritans called it, is still within. The flesh is weak: never forget it. Don't you be overconfident, self-reliant, not in anything; it is the key to the Christian life.