Well, isn't Eru (Illuvatar) really supposed to be God. I suppose there is one main difference: nowhere in ant of Tolkien's writings is there any mention of the doubt of Eru's existence. It is always said as if he were definitely real, whereas all our religions, to none of which I belong, by the way, are much less definite. Any religious figure would probably say, when asked, that one has to find God within oneself. This is the key difference between whatTolkien created and what many of us believe (sorry if I am in any way out of line here
Tolkien's original aim, when he was young, was to
...make a body of more or less connected legend, ranging from the large and cosmogonic, to the level of romantic fairy story...which I could dedicate simply to: to England; to my country.
Probably his main reason for aspiring to this was that
There was...nothing [by way of myth] English. Of course therewas and is all the Arthurian world, but...it is involved in, and explicitly contains, the Christian religion.
Tolkien wanted to create a world without any doubtable religious beliefs as we know them, which is why he all his writings about Eru are made to appear completely true and factual.
Just a thought.
Any other views on the matter?