Brian Nolder in an essay entitled God and Hobbits quotes Tolkien who writing to a friend observed:
The Lord of the Rings is of course a fundamentally religious and Catholic work;…
The problem lies in the fact that there is nothing overtly religious in the surface of LOTR. As Tom Shippey notes,
The hobbits, for all their nineteenth-century Englishness, are devoid of any religious sanction for any of their activities. We know they get married,…But they have no churches, and there is no hint as to who marries them.
Tolkien clarifies his statement with the following:
…The religious element is absorbed into the story and the symbolism.
For Tolkien, the story does not need to be outwardly religious in order to manifest religious themes. Religion is perfectly capable of embedding itself in the signs and symbols of a story.
In fact, the best stories are replete with gospel symbolism without ever mentioning the gospel. The reason is, to paraphrase Van Til, “the gospel is indelibly engraved upon the world.”
Part of what Tolkien was trying to achieve in writing LotR was to create a Pre-Christian Christian mythology for England. He did not mention religion or any major form of worship/spirituality due to a desire to avoid any semblance of paganism. As Tolkien states, in the quote above, he suffused the work with Christian symbolism and virtues instead.