So related to the issue of Satanism that it is often mentioned mere sentences away from it by those who see either as a problem. Formally speaking Syncretism is merely the blending of foreign elements with any culture or tradition. Christianity already has a fair bit of it, much of it from similar roots, and yet some still take offense to the blending of Christian ideals and Pagan symbols in a work of fiction. This might not be such a issue if some Christian fans of the works didn't constantly try and argue the point.
As is demonstrated in the blockqoute to the right here, some vocal if very few people insist that as a good, practicing Catholic, Tolkien condemned himself to hell for preaching such paganism; or that's how they imagine it anyway. As a scholar of Norse Mythology it is not entirely unreasonable to expect some of this to show in his writing, indeed many of his character names come from the Poetic Edda (Gandalf being the prime example). This is not the limit to the influences that can be found in his work of this nature (Burns, 2005), but most have no problem with their fiction being very diverse in its origins.
As anyone who has heard of Saturnalia knows, Christmas isn't the first major winter holiday to occur near the the solstice, nor is Christmas altogether unique in its festivities And Christmas sin't the only example, just the most pertinent at present. It was simply a matter of being accommodating to the people who they were attempting to convert at the time. Especially as the Roman Empire became officially Christian, many traditions of the Roman Cults were retained culturally or appropriated into Christianity (as in Christmas and Easter).
Indeed, even those who have a problem with Christianity having so many Pagan traditions already wouldn't take so much offense to the works if other Christians (fans of the work) didn't keep espousing how well this reflects biblical ideals (THE LORD OF...). By suggesting that they should read the work looking for their ideals, it primes them to find the parts they disagree with or take offense too. Even if most people would just chuckle at a wizard in a story, some of those same people get quite uncomfortable when others identify said wizard as a Jesus character.
Burns, Marjorie (2005). Perilous Realms: Celtic and Norse in Tolkien's Middle-earth. Toronto: University of Toronto Press. ISBN 0-8020-3806-9.
In his personal letters (many are included in a book titled The Letters of J. R. R Tolkien), he expressed caution toward occult practices. But he equipped his team of mythical heroes -- the fellowship of the Ring -- with the pagan powers that God forbids. For example, "Gandalf [a helpful wizard] is able to wield potent magic... To do battle with the forces of darkness, Gandalf the Grey can call upon not only his spellcraft, but also his staff of power and the Elven sword Glamdring."
Tolkien, himself, assures us that he didn't intend to teach Biblical reality through his mythical fantasy. In a 1956 letter he wrote, "There is no 'allegory' -- moral, political, or contemporary -- in the work at all. It is a 'fairy-story' ... [written] for adults.
Yet, many Christians argue that Tolkien's spiritual hierarchy does indeed parallel the Biblical account. Even Tolkien, in spite of his denials, has compared parts of his myth with corresponding aspects of truth. But the obvious similarities tend to confuse rather than clarify Biblical truth. For Tolkien's myth twists Scriptures enough to change their meanings and muddle the true nature of God. Like the serpent's temptation in the garden, Tolkien's illusions of truth appeal to human feelings and may lead to deception.
THE LORD OF THE RINGS: PAGANISM, CHRISTIANITY OR SYNCRETIZED CHRISTIANITY?, The Cutting Edge, http://www.cuttingedge.org, Web Nov 29th 2012