Is it impolite to be on a first name basis with God?
I often teach men and women who return to college later in life to complete a degree. It is not unusual that some of them are older than I am, and I often invite them to use my given name, John. Very few take me up on the offer. When I ask why, they say it just doesn't seem right. "You're the professor," they insist.
Some of these same dynamics may have been at work in the Vatican this summer, when the Congregation for Divine Worship directed that the proper name of God, Yahweh, not be used in any manner during the liturgy.