I have mused this thought over in my head many times, but was not sure how to state it, so this might sound sort of rough.
The Silmarillion to me is basically a creation story, much in the vein of the Bible, Quaran, Torah. The beginning of the Silmarillion, the Ainulindale, reads like Genesis in a way. Now I am certainly not trying to say that this is the only religious connection Tolkien has, definitely not. But it seems that just as with most any religion, there needs to be a creation story. Here is a question for my friends who follow religions I am not knowledgable about. Do all religions or cultures have a creation myth or story?

And lastly it is interesting that Tolkien wrote a creation myth. In my own mind, perhaps this is one of the main reasons why Tolkien's work seems more...beleivable in a way. Now don't get me wrong, I know that there are no dwarfs and elves and so on. But these were the legends and beliefs of many of my ancestors. Maybe Tolkien thought that a creation myth would make his work more thorough or complete. I'll ahave more thoughts on this. Students call.