What is the nature of the problem of man not knowing the significance of God’s name and not accepting God’s new name?

Relevant Words of God:

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.