The Answer from God’s Word:
What is the most basic principle in seeking the true way? You have to look at whether or not there is the work of the Holy Spirit, whether or not these words are the expression of the truth, who is testified to, and what it can bring you. Distinguishing between the true way and the false way requires several aspects of basic knowledge, the most fundamental of which is to tell whether or not there is the work of the Holy Spirit. For the substance of man’s belief in God is the belief in the Spirit of God, and even his belief in God incarnate is because this flesh is the embodiment of the Spirit of God, which means that such belief is still the belief in the Spirit. There are differences between the Spirit and the flesh, but because this flesh comes from the Spirit, and is the Word become flesh, thus what man believes in is still the inherent substance of God. And so, in distinguishing whether or not it is the true way, above all you must look at whether or not there is the work of the Holy Spirit, after which you must look at whether or not there is the truth in this way. This truth is the life disposition of normal humanity, which is to say, that which was required of man when God created him in the beginning, namely, all of normal humanity (including human sense, insight, wisdom, and the basic knowledge of being man). That is, you need to look at whether or not this way takes man into a life of normal humanity, whether or not the truth that is spoken of is required according to the reality of normal humanity, whether or not this truth is practical and real, and whether or not it is most timely. If there is truth, then it is able to take man into normal and real experiences; man, furthermore, becomes ever more normal, man’s human sense becomes ever more complete, man’s life in the flesh and the spiritual life become ever more orderly, and man’s emotions become ever more normal. This is the second principle. There is one other principle, which is whether or not man has an increasing knowledge of God, whether or not experiencing such work and truth can inspire a love of God in him, and bring him ever closer to God. In this can be measured whether or not it is the true way. Most fundamental is whether this way is realistic rather than supernatural, and whether or not it is able to provide the life of man. If it conforms to these principles, the conclusion can be drawn that this way is the true way. … If it is the work of the Holy Spirit, man becomes ever more normal, and his humanity becomes ever more normal. Man has an increasing knowledge of his disposition, which has been corrupted by Satan, and of the essence of man, and he has an ever greater longing for the truth. That is to say, the life of man grows and grows, and the corrupt disposition of man becomes capable of more and more changes—all of which is the meaning of God becoming the life of man. If a way is incapable of revealing those things that are the essence of man, is incapable of changing the disposition of man, and, moreover, is incapable of bringing him before God or giving him a true understanding of God, and even causes his humanity to become ever more lowly and his sense ever more abnormal, then this way must not be the true way, and it may be the work of an evil spirit, or the old way. In short, it cannot be the present work of the Holy Spirit. … If you grasp these several key principles, then whatever happens you will not be deceived.
from “Only Those Who Know God and His Work Can Satisfy God” in The Word Appears in the Flesh