Why doesn’t the Lord appear to man and work in a spiritual body when He comes back in the last day?
The answer from Almighty God’s word:
“God of the last days principally uses the word to make man perfect. He does not use signs and wonders to oppress man, or convince man; this cannot make plain the power of God. If God only showed signs and wonders, then it would be impossible to make plain the reality of God, and thus impossible to make man perfect. God does not make man perfect by signs and wonders, but uses the word to water and shepherd man, after which is achieved the complete obedience of man and man’s knowledge of God. This is the aim of the work He does and the words He speaks. God does not use the method of showing signs and wonders to make man perfect—He uses words, and uses many different methods of work to make man perfect. Whether it be the refinement, dealing, pruning, or provision of words, God speaks from many different perspectives to make man perfect, and to give man a greater knowledge of the work, wisdom and wondrousness of God. When man is made complete at the time that God concludes the age in the last days, he will be qualified to look upon signs and wonders. When you have a knowledge of God and are able to obey God no matter what He does, you will see signs and wonders, for you will have no conceptions about the reality of God. At the moment, you are corrupt and incapable of complete obedience to God—are you qualified to see signs and wonders? The time that God shows signs and wonders is when God punishes man, and also when the age changes, and, moreover, when the age concludes. When God’s work is being carried out normally, He does not show signs and wonders. Showing signs and wonders is supremely easy, but that is not the principle of God’s work, nor is it the aim of God’s management of man. If man saw signs and wonders, and if the spiritual body of God were to appear to man, would all people not ‘believe’ in God? I have previously said that a group of overcomers are gained from the East, overcomers who come from amid the great tribulation. What is the meaning of such words? They mean that these people who have been gained only truly obeyed after undergoing judgment and chastisement, and dealing and pruning, and all kinds of refinement. The belief of such people is not vague and abstract, but real. They have not seen any signs and wonders, or any miracles; they do not speak of abstruse letters and doctrines, or profound insights; instead they have reality, and the words of God, and a true knowledge of the reality of God. Is such a group not more capable of making plain the power of God?”
from “All Is Achieved by the Word of God” in The Word Appears in the Flesh