The answer from God’s word:
To man, God’s crucifixion concluded the work of God’s incarnation, redeemed all of mankind, and allowed Him to seize the key to Hades. Everyone thinks God’s work has been fully accomplished. In actuality, to God, only a small part of His work has been accomplished. He has only redeemed mankind; He has not conquered mankind, let alone changed the ugliness of Satan in man. That is why God says, “Although My incarnate flesh went through the pain of death, that was not the whole goal of My incarnation. Jesus is My beloved Son and was nailed to the cross for Me, but He did not fully conclude My work. He only did a portion of it.” Thus God began the second round of plans to continue the work of the incarnation. God’s ultimate intention is to perfect and gain everyone rescued from Satan’s hands, which is why God prepared again to risk dangers to come into flesh.
from “Work and Entry (6)” in The Word Appears in the Flesh
… in the Age of Grace, the demons went away from man with the laying on of hands and prayer, but the corrupt dispositions within man still remained. Man was healed of his sickness and forgiven his sins, but the work for just how the corrupt satanic dispositions within man could be cast away was not done in him. Man was only saved and forgiven his sins for his faith, but the sinful nature of man was not taken away and still remained within him. The sins of man were forgiven through God incarnate, but it does not mean that man has no sin within him. The sins of man could be forgiven through the sin offering, but man has been unable to resolve the issue of just how he can no longer sin and how his sinful nature can be cast away completely and be transformed. The sins of man were forgiven because of the work of God’s crucifixion, but man continued to live in the old, corrupt satanic disposition. As such, man must be completely saved from the corrupt satanic disposition so that the sinful nature of man is completely cast away and never again develops, thus allowing the disposition of man to be changed. This requires man to understand the path of growth in life, the way of life, and the way to change his disposition. It also needs man to act in accordance with this path so that the disposition of man can gradually be changed and he can live under the shining of the light, and that he can do all things in accord with the will of God, cast away the corrupt satanic disposition, and break free from Satan’s influence of darkness, thereby emerging fully from sin. Only then will man receive complete salvation. … Therefore, after that stage was complete, there is still the work of judgment and chastisement. This stage makes man pure through the word so as to give man a path to follow. This stage would not be fruitful or meaningful if it continued with the casting out of demons, for the sinful nature of man would not be cast away and man would only stop upon the forgiveness of sins. Through the sin offering, man has been forgiven his sins, for the work of the crucifixion has already come to an end and God has prevailed over Satan. But the corrupt disposition of man still remains within them and man can still sin and resist God; God has not gained mankind. That is why in this stage of work God uses the word to reveal the corrupt disposition of man and asks man to practice in accordance with the right path. This stage is more meaningful than the previous one and more fruitful as well, for now it is the word that directly supplies man’s life and enables the disposition of man to be completely renewed; it is a stage of work more thorough. Therefore, the incarnation in the last days has completed the significance of God’s incarnation and completely finished God’s management plan for the salvation of man.
from “The Mystery of the Incarnation (4)” in The Word Appears in the Flesh
Why is it said that the practice of those in the religious churches is outdated? It is because what they put into practice is divorced from the work of today. In the Age of Grace, what they put into practice was right, but as the age has passed and God’s work has changed, their practice has gradually become outdated. It has been left behind by the new work and the new light. Based upon its original foundation, the work of the Holy Spirit has progressed several steps deeper. Yet those people still remain stuck at the original stage of God’s work, and still cleave to the old practices and the old light. God’s work can change greatly in three or five years, so would not even greater transformations occur over the course of 2,000 years? If man has no new light or practice, it means that he has not kept up with the work of the Holy Spirit. This is the failing of man; the existence of God’s new work cannot be denied because, today, those with the Holy Spirit’s original work still abide by outdated practices. The work of the Holy Spirit is always moving forward, and all those who are in the stream of the Holy Spirit should also be progressing deeper and changing, step-by-step. They should not stop at a single stage. Only those who do not know the work of the Holy Spirit would remain amongst His original work, and not accept the new work of the Holy Spirit. Only those who are disobedient would be incapable of gaining the Holy Spirit’s work. If the practice of man does not keep pace with the new work of the Holy Spirit, then the practice of man is surely dissevered from the work of today, and is surely incompatible with the work of today. Such outdated people as these are simply incapable of accomplishing God’s will, much less could they become those final people that will stand testimony to God. The entire management work, furthermore, could not be concluded amongst such a group of people. For those who once held to the law of Jehovah, and those who once suffered for the cross, if they cannot accept the stage of work of the last days, then all that they did will have been in vain, and useless. …
… In each period of time, God will begin new work, and in each period, there will be a new beginning among man. If man only abides by the truths that “Jehovah is God” and “Jesus is Christ,” which are truths that only apply to a single age, then man will never keep up with the work of the Holy Spirit, and will forever be incapable of gaining the work of the Holy Spirit. … Many even believe that all those who reject the old law and accept the new work are without conscience. These people, who only talk of conscience, and do not know the work of the Holy Spirit, will ultimately have their prospects cut short by their own consciences. God’s work does not abide by doctrine, and even though it is His own work, still God does not cling to it. That which should be denied is denied, that which should be eliminated is eliminated. Yet man places himself in enmity of God by holding onto but one small part of the work of God’s management. Is this not the absurdity of man? Is this not the ignorance of man? The more that people are timid and overcautious because they are afraid of not gaining God’s blessings, the more that they are incapable of gaining greater blessings, and of receiving the final blessing. Those people who slavishly abide by the law all display the utmost loyalty toward the law, and the more they display such loyalty toward the law, the more they are rebels who oppose God. For now is the Age of Kingdom and not the Age of Law, and the work of today cannot be held up against the work of the past, and the work of the past cannot be compared to the work of today. The work of God has changed, and the practice of man has also changed; it is not to hold onto the law or bear the cross. So, people’s loyalty toward the law and the cross will not gain God’s approval.
from “God’s Work and Man’s Practice” in The Word Appears in the Flesh
Because there are always new developments in God’s work, thus there is new work, and thus there is also work that is obsolete and old. This old and new work is not contradictory, but complementary; each step follows on from the last. Because there is new work, the old things must, of course, be eliminated. … The work of God is always new and never old, and it never forms doctrine and is, instead, continually changing and renewing to a greater or lesser extent. This work is the expression of the inherent disposition of God Himself. It is also the inherent principle of God’s work, and one of the means by which God accomplishes His management. If God did not work in this way, man would not change or be able to know God, and Satan would not be defeated. Thus, in His work there continually occur changes that appear erratic, but which are actually periodic. The way in which man believes in God, however, is quite different: He clings to old, familiar doctrines and systems, and the older they are the more palatable they are to him. How could the foolish mind of man, a mind that is as intransigent as stone, accept so much unfathomable new work and words of God? … God’s intention has always been for His work to be new and alive, not old and dead, and that which He makes man hold firm to is divided into ages and periods, not everlasting and immutable. That is because He is a God who causes man to live and be new, rather than a devil who causes man to die and be old. Do you still not understand this? You have conceptions about God and are incapable of letting go of them because you are closed-minded. It is not because there is too little sense to God’s work, or because the work of God is inhumane—nor, moreover, is it because God is always “negligent in His duties.”
from “Only Those Who Know the Work of God Today Can Serve God” in The Word Appears in the Flesh