Watchman Nee saw from the Scriptures that to sin and die is a law (Rom. 8:2). This law is in the members of our body (Rom. 7:23) and is derived from the evil life of Satan. Every fallen man is under its power. But the law of the Spirit of life is more powerful than the law of sin and death and is able to free us from it.
The new covenant which the Lord Jesus enacted for us with His blood is better than the old covenant (Heb. 7:22; 8:6). The old covenant is according to the Old Testament law, with a priesthood according to the law of a fleshy commandment; whereas, the new covenant is according to the law of life, with a priesthood according to the power of an indestructible life (Heb. 8:10; 7:16).
Because Christ has overcome Satan and every negative thing in the universe, His life is an overcoming life. If we live by Christ, His life overcomes every negative thing for us.
Watchman Nee received revelation concerning the calling of the overcomers. Because the whole church has become defeated, failing to meet the Lord's purpose, the Lord has come in to call some of His believers to be overcomers. This is clearly revealed in the seven epistles in Revelation 2 and 3. Because the whole church has missed the mark, the Lord has sounded His call to those who love Him to overcome the degraded church.
By 1925 Watchman Nee had seen the matter of spiritual warfare. He saw that for the accomplishment of God's divine purpose in this universe, there is a consummate battle shaping up between God and His enemy, Satan. This battle involves all of God's children. If they take sides with Satan, they are rebelling against God; if they take sides with God, they are fighting against Satan. All the overcoming believers must realize that they are on the battlefield; they are fighting for God's divine purpose. To fight in this spiritual warfare requires the believer to see his heavenly position. Ephesians 2 makes it clear that we are seated in the heavenly places, and Ephesians 6 indicates that we are fighting against the powers in the heavenlies. The believers must keep their heavenly position so that they can defeat God's enemies in the heavenly places. If the believers' position is on the earth, they are under the enemy, and they lose the position to overcome.