I don't know. We all bring something of ourselves to whatever we choose to create. Our experiences certainly play a huge part in the creative process. We write what we know. We write what we believe.
If we fail to do that, we are inauthentic to ourselves and our audience.
I don't believe that Tolkien was at all inauthentic. There are few writers who know the genre as he did; still fewer who could create not just a mythical/fantastical world but one complete with its own language.
At the end of the day, does it really make any difference if he avowed or disavowed being a Catholic or a Christian?
In any event, what Tolkien created has engaged, enthralled, and given enjoyment to countless people and multiple generations of readers.
Thanks for the read.