The answer from God’s word:
To study such a thing is not difficult, but requires each of us to know this truth: He who is God’s incarnation shall hold the substance of God, and He who is God’s incarnation shall hold the expression of God. Since God becomes flesh, He shall bring forth the work He must do, and since God becomes flesh, He shall express what He is, and shall be able to bring the truth to man, bestow life upon man, and show man the way. Flesh that does not contain the substance of God is surely not the incarnate God; of this there is no doubt. To investigate whether it is God’s incarnate flesh, man must determine this from the disposition He expresses and the words He speaks. Which is to say, whether or not it is God’s incarnate flesh, and whether or not it is the true way, must be judged from His substance. And so, in determining[a] whether it is the flesh of God incarnate, the key is to pay attention to His substance (His work, His words, His disposition, and many more), rather than external appearance. If man sees only His external appearance, and overlooks His substance, then that shows the ignorance and naivety of man. External appearance does not determine substance; what’s more, the work of God has never conformed with the conceptions of man. Did not the outward appearance of Jesus conflict with the conceptions of man? Were not His appearance and dress unable to provide any clues as to His true identity? Was not the reason why the earliest Pharisees opposed Jesus because they merely looked at His external appearance, and did not take to heart the words that He spoke? It is My hope that the brothers and sisters who seek the appearance of God will not repeat the tragedy of history. You must not become the Pharisees of modern times and nail God to the cross again. You should carefully consider how to welcome the return of God, and should have a clear mind of how to be someone who submits to the truth. This is the responsibility of everyone who is waiting for Jesus to return with the clouds. We should rub our spiritual eyes, and not fall prey to the words full of flights of fancy. We should think about the practical work of God, and should take a look at the real side of God. Do not get carried away or lose yourselves in daydreams, always looking forward to the day that the Lord Jesus suddenly descends among you on a cloud to take you who have never known Him or seen Him, and do not know how to do His will. It is better to think upon practical matters!
from Preface to The Word Appears in the Flesh
God become flesh is called Christ, and so the Christ that can give people the truth is called God. There is nothing excessive about this, for He possesses the substance of God, and possesses God’s disposition, and wisdom in His work, that are unattainable by man. Those who call themselves Christ, yet cannot do the work of God, are frauds. Christ is not merely the manifestation of God on earth, but instead, the particular flesh assumed by God as He carries out and completes His work among man. This flesh is not one that can be replaced by just any man, but one that can adequately bear God’s work on earth, and express the disposition of God, and well represent God, and provide man with life. Sooner or later, those fake Christs will all fall, for although they claim to be Christ, they possess none of the substance of Christ. And so I say that the authenticity of Christ cannot be defined by man, but is answered and decided by God Himself.
from “Only Christ of the Last Days Can Give Man the Way of Eternal Life” in The Word Appears in the Flesh
There are some who are possessed by evil spirits and persistently cry out, “I am God!” Yet in the end, they cannot remain standing, for they act on behalf of the wrong being. They represent Satan and the Holy Spirit pays them no attention. However highly you exalt yourself or however strongly you cry out, you are still a created being and one that belongs to Satan. I never cry out, I am God, I am the beloved Son of God! But the work I do is God’s work. Need I shout? There is no need for exaltation. God does His work Himself and does not need for man to accord Him a status or honorific title, and His work is sufficient to represent His identity and status. … You cannot bring forth new paths or represent the Spirit. You cannot express the work of the Spirit or the words that He speaks. You cannot do the work of God Himself or that of the Spirit. You cannot express the wisdom, wonder, and unfathomableness of God, or all the disposition by which God chastises man. So your repeated claims to be God do not matter; you have only the name and none of the substance. God Himself has come, but none recognize Him, yet He continues on in His work and does so in representation of the Spirit. Whether you call Him man or God, the Lord or Christ, or call Her sister, it is all right. But the work He does is that of the Spirit and represents the work of God Himself. He does not care about the name by which man calls Him. Can that name determine His work? Regardless of what you call Him, from the perspective of God, He is the incarnate flesh of the Spirit of God; He represents the Spirit and is approved by Him. You cannot make way for a new age, and you cannot bring the old to an end and cannot usher in a new age or do new work. Therefore, you cannot be called God!
from “The Mystery of the Incarnation (1)” in The Word Appears in the Flesh
If, during the present day, there is to emerge a person who is able to display signs and wonders, and can cast out demons, and heal, and perform many miracles, and if this person claims that they are the coming of Jesus, then this would be the counterfeit of evil spirits, and their imitation of Jesus. Remember this! God does not repeat the same work. Jesus’ stage of work has already been completed, and God will never again undertake that stage of work. The work of God is irreconcilable with the conceptions of man; for example, the Old Testament foretold the coming of a Messiah, but it turned out that Jesus came, so it would be wrong for another Messiah to come again. Jesus has already come once, and it would be wrong if Jesus were to come again this time. There is one name for every age, and each name is characterized by the age. In the conceptions of man, God must always display signs and wonders, must always heal and cast out demons, and must always be just like Jesus, yet this time God is not like that at all. If, during the last days, God still displayed signs and wonders, and still cast out demons and healed—if He did exactly the same as Jesus—then God would be repeating the same work, and the work of Jesus would have no significance or value. Thus, God carries out one stage of work in every age. Once each stage of His work has been completed, it is soon imitated by evil spirits, and after Satan begins to follow on the heels of God, God changes to a different method; once God has completed a stage of His work, it is imitated by evil spirits. You must be clear about these things. Why is the work of God today different to the work of Jesus? Why does God today not display signs and wonders, not cast out demons, and not heal? If Jesus’ work were the same as the work done during the Age of Law, could He have represented the God of the Age of Grace? Could Jesus have completed the work of crucifixion? If, as in the Age of Law, Jesus had entered into the temple and kept the Sabbath, then He would have been persecuted by none and embraced by all. If that were so, could He have been crucified? Could He have completed the work of redemption? What would be the point if God incarnate of the last days displayed signs and wonders, like Jesus? Only if God does another part of His work during the last days, one that represents part of His management plan, can man gain a deeper knowledge of God, and only then can God’s management plan be completed.
from “Knowing God’s Work Today” in The Word Appears in the Flesh
a. The original text reads “as for.”