Purport

In earlier Shlokas, Bhagvan Shri Krishna explained one of the most important spiritual facts, why humans are not able to witness or see God?

Living beings have been material entities that lie within limits of material nature and three Gunas(modes of nature). Bhagvan Shri Krishna, God, on the other hand, is beyond the bounds of material nature and Gunas, together known as Maya. For this reason, the human is not able to witness God.

This phenomenon is common to all human and living beings. But there exists one subtle difference. A sensible person recognizes this limitation and tries to get out of it. He may try any path of Yoga as per his personal orientation. Yet more alert person submits himself to Bhagvan Shri Krishna. Such people are able to get out of the bounds of material limitations sooner or later (The whole process was explained in Chapter 6).

But there are other kinds of people, who take their physical body and their physical experience as absolute truth. They don’t recognize anything beyond their personal experience. Even worse is that fail to recognize God even when God appears to them in physical form during the Incarnation.
Shloka 11 of Ch9, explain it like this:
“Not realizing My existence as the Supreme form of the Almighty, fools disregard me when I am in human form.”

Such human when they are unable to see God due to own physical limitation assume God does not exist. But when Shri Krishna God, incarnates and appears in mortal form, such people then say, but He is human.

Such people are under the effect of the delusion of Maya. Such people are got caught in never-ending cycle birth and death where they keep floating between pleasure and sorrow.