This is a handful question ...

Since man ate of the tree of the knowledge of good and evil, which signifies Satan, Satan's nature entered into man. This nature incites and stirs up man to endeavor to do good that he may please God. This becomes a vice of the fallen sinner. Some may be shocked upon hearing this, thinking that all religionists exhort and encourage people to do good, and they may wonder why I say that man's desire to do good is incited by Satan. Parents like to encourage their children to do good, and even you yourself have an inner desire to do good. Is it good or bad to determine to do good and to encourage others to do good? From man's standpoint, it is good. Today's society everywhere encourages people to do good. As far as human society is concerned, this is good, but as far as the accomplishing of God's economy is concerned, this is not good and is something against God.

God's intention in His economy is to accomplish a goal, that is, for the Divine Trinity to gain man to be His organism. God's economy is not to work out man's goodness; to work out man's goodness is something of God's enemy. Human goodness is God's enemy. What God wants is to have an organism that lives out God to express God, manifest God, and be joined with God as one. Such a living organism is what God wants. From the viewpoint of God's economy, for man to do good is for man to be in enmity with God.

Before the law was given, God first gave man a sweet promise; He promised the fallen sinner that the seed of woman would come. This seed of woman would destroy the enemy, the serpent, who had damaged man. The seed of woman would become man's righteousness and man's salvation. Prior to His coming, however, man would neither believe nor receive Him. Therefore, God had to decree His law to man. The law was not there in the origination of God's economy. It was added because of man's transgressions, while God's economy was proceeding (Gal. 3:19). Due to man's fall and his not knowing himself, God was forced to insert, to add, the law. To add implies that something was not there originally. The law was not there originally but was added later in order to expose man's real condition and true nature and thus show man the true picture of himself.

The Law of God Being a Portrait and Testimony of God

The law of God is a portrait and testimony of God. In Romans 7 Paul says that the law is holy and spiritual and the commandment is holy, righteous, and good (vv. 12, 14). The law is good, holy, and spiritual, yet even so, it is only a portrait, a "photo" of God. The law describes to us what kind of God He is, what kind of image He bears, and what kind of attributes He possesses. Hence, the law as God's portrait is called "the testimony" of God in the Old Testament (Exo. 32:15; Psa. 78:5). God's portrait, God's description, is God's testimony. Your photo is your testimony. When you give me a picture of yourself, you testify to me what kind of person you are. The moment I look at the picture, I know what kind of person you are. Similarly, the law is a portrait and testimony of God. When we see the law of God, we know what kind of God He is.

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It Being Impossible for Sinners to Fulfill the Requirements of God's Law

The law, therefore, exposes our condition, showing us that it is impossible for sinners to fulfill the requirements of God's law. Although man cannot do good, he desires and wills to do good. Actually, man's condition is that he does not care for God; rather, he cares for things other than God. He does not take God as his satisfaction nor takes what God has accomplished as his enjoyment and rest; rather, he wants to strive by himself and bear the burdens alone. Today people have fallen into a condition of hatred, murder, and fornication. Today people commit fornication like those at the time of Sodom.

Since man's condition is such, God considers His law, His reality, as His requirements upon sinners. It is as if He says to man who desires to do good, "These are My requirements. Do you want to do good? Go ahead! If you can work out all the Ten Commandments, I will justify you." According to Romans 7, it seems that Paul was able to work out the first nine commandments, but he was not able to work out the last commandment concerning not coveting. The law of God makes it impossible for sinners to fulfill the requirements of God, because God's law is for the purpose of exposing man. It cannot give life (Gal. 3:21). The law as a "photo" is good, but it does not have life. Furthermore, there is something that the law cannot do, in that it is weak through the flesh of sinners (Rom. 8:3a). The law itself is not weak, but the flesh of man that tries to work out the law is weak, so the law became weak and impotent.

The Law of God Being Able Only to Expose Man's Sinful Nature and Wicked Deeds

Since the law cannot give life and is impotent, being weak through the flesh of sinners, why did God add the law? The law of God was added for the purpose of exposing man's inward, sinful nature and his outward, wicked deeds (Rom. 3:20b; 5:20a). We have violated every one of the Ten Commandments. The law is a mirror. When we stand before the mirror of the law, we all are exposed.

The Law of God Becoming the Custodian and Child-conductor of God's Chosen People to Bring Them to Christ-Grace

Nevertheless, the law of God has a positive function in God's hand. The law has become the custodian and child-conductor of God's chosen people to bring them to Christ-grace (Gal. 3:23-24). God's chosen people were shut up and guarded under the law, just like sheep being kept in the sheepfold (John 10:1, 16). In His economy God used the law as a sheepfold to keep His elect in custody until Christ came. The law was able only to demand and condemn; it could not give life. There is no life in the law; there are only commandments. Life is in Christ. He is the life-giving Spirit (1 Cor. 15:45b), the only One who is able to give life. When we are under law, we are just like children, and we need the law to be the custodian and child-conductor watching over us. This kind of watching over is not with an evil intention; it is for our protection. Hence, this custodian becomes our child-conductor, and this child-conductor brings us to Christ. Today Christ as the life-giving Spirit is the grace that we enjoy. When Christ comes, grace comes. He became flesh and was full of grace, and of His fullness we have all received, and grace upon grace. Now we are no longer children under the custody of the law. Rather, through our faith in Christ Jesus we have become children of God to enjoy Him as our grace.