Jehovah God could not have taken these actions and made them effective without a human manifestation, as various comparisons can illustrate.
An invisible person cannot shake hands or talk with a visible one. In fact, angels and spirits cannot shake hands or talk with us even when they are standing right next to our bodies or in front of our faces. No one’s soul can talk, or do things, with anyone else except through its own body. The sun cannot convey its light and heat into any human, animal, or tree, unless it first enters the air and acts through that. It cannot convey its light and heat to any fish unless it passes through the water. It has to act through the element the entity is in. None of us could scale a fish with a knife or pluck a raven’s feathers if we had no fingers. We cannot go to the bottom of a deep lake without a diving bell. In a word, one thing needs to be adapted to another before the two can communicate and work with or against each other.
from True Christianity, Volume 1, Section 125