Evidently, God was, for the very first time, "seen of angels" when they saw Him as a babe in the manger at Bethlehem (Luke 2:9-13). Before, He had been invisible to them as well as to man, "dwelling in the light which no man can approach unto" (1 Timothy 6:16). In this verse, "man" is not in the original text. No one may see God in His essential glory even though He has occasionally assumed human form in theophanies.

Source:

KJV Defenders Study Bible, by Dr. Henry Morris, Ph.D.
Publisher: Thomas Nelson
Language: English
DEF 10 ISBN 0-529-10444-x
DEF 10-1 ISBN 0-529-10445-8