We believe that when the Lord returns, man will be changed into a holy body in the blink of an eye, so why in the last days must God undertake judgment and cleansing work?

The Answer from God’s Word:

In His final work of concluding the age, God’s disposition is one of chastisement and judgment, in which He reveals all that is unrighteous, in order to publicly judge all peoples, and to perfect those who love Him with a sincere heart. Only a disposition such as this can bring the age to an end. The last days have already arrived. All things in creation will be classed according to their kind, and divided into different categories based on their nature. This is the moment when God reveals humanity’s outcome and their destination. If people do not undergo chastisement and judgment, then there will be no way of exposing their disobedience and unrighteousness.
Only through chastisement and judgment can the outcome of all creation be revealed. Man only shows his true colors when he is chastised and judged. Evil shall be put with evil, good with good, and all humanity shall be classified according to their kind. Through chastisement and judgment, the outcome of all creation will be revealed, so that the evil may be punished and the good rewarded, and all people become subject to the dominion of God. All this work must be achieved through righteous chastisement and judgment. Because man’s corruption has reached its peak and his disobedience become exceedingly severe, only God’s righteous disposition, one that is principally compounded of chastisement and judgment and is revealed during the last days, can fully transform and complete man. Only this disposition can expose evil and thus severely punish all the unrighteous.

from “The Vision of God’s Work (3)” in The Word Appears in the Flesh

No matter what the imaginings of man, the substance of God’s work cannot be altered. The imaginings of man are nothing but the constructs of man’s thoughts and come from the brain of man, summed up and pieced together from what man has seen and heard. Therefore I say, however brilliant the images conceived, they are still no more than a drawing and are not able to substitute for the plan of God’s work. After all, man has been corrupted by Satan, so how can he then fathom the thoughts of God? …

… In the last days, Christ uses a variety of truths to teach man, expose the essence of man, and dissect his words and deeds. These words comprise various truths, such as man’s duty, how man should obey God, how man should be loyal to God, how man ought to live out the normal humanity, as well as the wisdom and the disposition of God, and so on. These words are all directed at the essence of man and his corrupt disposition. In particular, those words that expose how man spurns God are spoken in regard to how man is an embodiment of Satan and an enemy force against God. In undertaking His work of judgment, God does not simply make clear the nature of man with just a few words; He exposes, deals with, and prunes it over the long term. These methods of exposure, dealing, and pruning cannot be substituted with ordinary words, but with the truth that man does not possess at all. Only methods of this kind are deemed judgment; only through judgment of this kind can man be subdued and thoroughly convinced into submission to God, and moreover gain true knowledge of God. What the work of judgment brings about is man’s understanding of the true face of God and the truth about his own rebelliousness. The work of judgment allows man to gain much understanding of the will of God, of the purpose of God’s work, and of the mysteries that are incomprehensible to him. It also allows man to recognize and know his corrupt substance and the roots of his corruption, as well as to discover the ugliness of man. These effects are all brought about by the work of judgment, for the substance of this work is actually the work of opening up the truth, the way, and the life of God to all those who have faith in Him. This work is the work of judgment done by God. … Those who come before God to be judged, and have moreover been purified, shall forever live in the kingdom of God.

from “Christ Does the Work of Judgment With the Truth” in The Word Appears in the Flesh

In the work of the last days, the word is mightier than the manifestation of signs and wonders, and the authority of the word surpasses that of signs and wonders. The word exposes all the corrupt dispositions buried deep in the heart of man. You have no way of recognizing them on your own. When they are laid bare before you through the word, you will naturally come to discover them; you will not be able to deny them, and you will be utterly convinced. Is this not the authority of the word? This is the result achieved by the work of the word today. … Before man was redeemed, many of Satan’s poisons had already been planted within him and, after thousands of years of being corrupted by Satan, he has within him an established nature that resists God. Therefore, when man has been redeemed, it is nothing more than a case of redemption in which man is bought at a high price, but the poisonous nature within him has not been eliminated. Man that is so defiled must undergo a change before becoming worthy to serve God. By means of this work of judgment and chastisement, man will fully come to know the filthy and corrupt substance within his own self, and he will be able to change completely and become clean. Only in this way can man become worthy to return before the throne of God. All the work done this day is so that man can be made clean and be changed; through judgment and chastisement by the word, as well as through refinement, man can purge away his corruption and be made pure. Rather than deeming this stage of work to be that of salvation, it would be more apt to say it is the work of purification. In truth, this stage is that of conquest as well as the second stage in the work of salvation. It is through judgment and chastisement by the word that man arrives at being gained by God; and it is through the use of the word to refine, judge, and disclose that all of the impurities, notions, motives, and individual aspirations within man’s heart are completely revealed. For all that man may have been redeemed and forgiven of his sins, it can only be considered as God not remembering the transgressions of man and not treating man in accordance with his transgressions. However, when man, who lives in a body of flesh, has not been set free from sin, he can only continue to sin, endlessly revealing his corrupt satanic disposition. This is the life that man leads, an endless cycle of sinning and being forgiven. The majority of men sin in the day only to confess in the evening. This way, even if the sin offering is forever effective for man, it will not be able to save man from sin. Only half the work of salvation has been completed, for man still has a corrupt disposition. … It is not easy for man to become aware of his sins; he has no way of recognizing his own deeply rooted nature, and must rely on judgment by the word in order to achieve this result. Only thus can man gradually be changed from this point onward. Man shouted thus in the past because he had no understanding of his original corrupt disposition. These are the impurities that exist within man. Throughout such a long period of judgment and chastisement, man lived in an atmosphere of tension. Was this not all achieved through the agency of the word? Did you not also cry out with a very loud voice prior to the trial of service-doers? “Enter the kingdom! All those who accept this name shall enter into the kingdom! All shall partake of God!” When the trial of service-doers came, you no longer cried out. At the very beginning, all cried out, “Oh God! Wherever You place me, I shall submit to being steered by You.” Upon reading the words of God, “Who will be My Paul?” man said, “I am willing!” Then he saw the words, “And what of the faith of Job?” and said, “I am willing to take upon myself the faith of Job. God, please put me to the test!” When the trial of service-doers came, he collapsed at once and almost could not stand up again. After that, little by little, the impurities in man’s heart gradually diminished. Was this not achieved through the word? So, what you have experienced today are results achieved through the word, even greater than those achieved through Jesus’ working of signs and wonders. …

… men would all submit to the voice, falling down without words of revelation, much in the way that Paul fell to the ground in the light on the road to Damascus. If God continued to work in this way, man would never be able to come to know his own corruption through judgment by the word and thereby attain salvation. Only through becoming flesh can He personally deliver His words into the ears of each and every human being, so that all who have ears may hear His words and receive His work of judgment by the word. Only this is the result achieved by His word, rather than the Spirit becoming manifest to frighten man into submission. It is only through this practical and yet extraordinary work that the old disposition of man, hidden deep within for many years, can be fully exposed, so that man may recognize it and have it changed. These things are all the practical work of God incarnate, in which, speaking and executing judgment in a practical manner, He achieves the results of judgment upon man by the word. This is the authority of God incarnate and the significance of God’s incarnation.

from “The Mystery of the Incarnation (4)” in The Word Appears in the Flesh

God is almighty. God has a practical side that people don’t see. People always think of God as impractical, unrealistic—they think that He just does any old thing He thinks up without any particular meaning. They think that the meaning in God’s eyes is just made up stuff—as if He just says whatever He wants to. People should know that within this is the truth. The way in which God works is meaningful, is bound by necessity and achieves the best effect. It is all done with regard to a specific purpose, meaning and plan. You think God’s work is all just done at random? He has an all-powerful aspect, but He also has a practical aspect. … No matter what stage of the work He is engaged in, He always works practically. It’s not as some believe, that God doesn’t think or speak and does whatever He feels like. He has wisdom and His being, this is His substance. In doing His work, He needs substance, wisdom and for all of His disposition to be revealed and issued forth for man to receive. He doesn’t work groundlessly. He speaks in a practical way, He does His work day-by-day….

from “One Must Know the Way in Which God Works” in Records of Christ’s Talks

With regard to His practical side, God incarnate endured much suffering in His thirty-three and a half years on earth, in the end being crucified until His blood ran dry. He endured the most terrible suffering but then was resurrected from death. His resurrection was God’s aspect of almightiness at work. He did not make any indication, or shed any blood or make it rain and say this was a sin offering. He didn’t do anything like that, but instead He personally became flesh to make contact with the whole of mankind and was nailed to the cross, so that mankind would know of this deed. By means of this deed, mankind came to know that God had redeemed them and this was proof that God had indeed saved man.

from “How to Understand God’s Almightiness and Practicality” in Records of Christ’s Talks