In our experience, death to self is deeper and more advanced than death to sin. Usually God’s children pay much attention to overcoming sins. They suffer much the harassment of sin. They know very well how that after they sin, their regenerated life grieves over the evil and bitterness of sin. They have tasted much of this, and they hope very much to overcome sin and to be no longer a slave of sin. Therefore, after they have received the light, and have realized how to die with the Lord, and how to reckon themselves dead to sin, they rely on the power of the Holy Spirit and begin to seriously reckon themselves dead, and to allow the victory of the cross to be expressed in their heart and through them. Yet, frequently there is something lacking: after they have the experience of victory over sin, they think that it is the highest form of life and that nothing can be higher. They pay too much attention to their sins. As a result, once they overcome them, they become satisfied. It is right for us to pay attention to our sins, and it is right for believers not to neglect their sins. Victory over sins is the basis of all righteousness and is the key to proper Christian living. If sin has dominion over us, we cannot expect to have any spiritual progress. But this does not mean that we can stop at victory over sin, and can draw a boundary line and call an end to our advance. We have to know that this is only the first step of the regeneration of a Christian. There is still a long way before us. Do not consider it an end! After overcoming sins, the immediate problem facing the believers is how to overcome the "self."
Believers often misunderstand the true meaning of "self." Some confuse self with sin. They consider self as sin and believe it should be put to death. Naturally, self and sin have a lot to do with each other, but self is not sin. They use the yardstick with which they measure sin to measure every outward behavior. Anything they consider wrong they condemn as sin and regard such a thing as self and as the "mother" of sin, and that it ought to be crucified. Little do they realize that as bad as the self is, it is not always evil. It is true that everything that springs from the "mother" of sin is sin, and is corrupt and defiled, and it is also true that what is expressed by the "mother" of sin through the self can in no way be good. However, sometimes when the self is expressed, it can appear very good in man’s eyes and can appear very virtuous, very kind, and very righteous. If we take the yardstick with which we measure sin to measure the self, we will surely eliminate the evil part of the self and keep its good part—good, of course, according to man’s view. Because believers are unaware of the source of self and do not realize that it can produce that which both God and man condemn as evil, as well as that which is recognized by man as good, they remain in the realm of the "self" and fail to enter into the enjoyment of the full and rich life of God. Satan is most subtle; he hides this fact and keeps the believers in darkness, causing them to be contented with the experience of victory over sin and to stop looking for a higher experience—the experience of victory over the self.
The self life is just our natural life. The natural life has been affected by Adam’s fall and has become very corrupt. Through Adam’s fall, man has acquired the sinful nature. This sinful nature is intimately interwoven with the natural life, which is the self. Our self is just our ego; it is what constitutes our own individual personality. In other words, it is our soul. Because the sinful nature is so intimately related to the self, it is difficult to separate the two in their operation, that is, in their acts of sins. They are so united that as soon as the "mother" of sin moves, the self agrees and executes, and man commits the outward sins.
Of course, we can never make too clear a separation between self and sin. With an unbeliever, self and sin are as one, and it is very hard to separate them. The self is already able to transgress by itself. But sin, being so powerful, affects the self, dominates the self, suppresses the self, and forces the self to come up with more ideas to sin. Under the influence of Adam’s fall, the self is already corrupt to the uttermost. Now when it collaborates with sin, the two have little reason for conflict. Even though sometimes the conscience makes a very faint protest, it is so short and weak that it disappears in no time. The self and sin cooperate with each other so well that in unregenerated persons, the two are mixed together. To them, sin is just self incarnated. To them, self is just the many evils that appear in the fallen human life; it is just the root, the branches, and the leaves of sin. To them, self is not only the origin of sin, but the very life of sin. To them, sin is self, and self is sin. After a man is regenerated, in the initial stage of his Christian life, he still finds it difficult to differentiate in experience between sin and self. Later, as he receives more grace from God, and as the work of the cross and the power of the Holy Spirit become more apparent in him, he begins to separate sin from the self. Along the way in their Christian life, God’s children are gradually able to differentiate the self from sin. Those who have experienced Romans 6:11 will realize that though a man may have overcome sin, he may still not have overcome the self. To those believers who are advanced in life, victory over sin is easy, while victory over the self is very difficult. If a believer has the full experience of victory over the self, he will have attained the life that the apostles had.
(The Word of the Cross, Chapter 1, by Watchman Nee)