פירוש על קידושין 61:3

"The entire world is full": It implies that He extends and descends below. So one who stands with an upright posture appears as [if he] is pushing [God] away.

Since the previous source imagined God dwelling among human beings, these sources continue to discuss the ramifications of God actually living on earth. The first ramification is that God is everywhere—one cannot hide from God. Sinning in secret is akin to making the theological statement that God is not in a certain place. I should note that there are sources that contradict this and seem to say that sinning in secret is preferable to sinning in public.
The second two statements deal with the proper posture and clothing to acknowledge that God is only slightly above one’s head. This last statement is one of the sources used to prove that Jews must keep their heads covered.