Not explicitly so. That being said, Tolkien certainly used themes that would have been known within some Catholic traditions of the middle of the 20th century, specifically a "watchmaker God", a mortal world that was degenerate and forever degenerating more, hosts of angelic and semi-angelic beings acting as intermediary forces, a Satan-figure who was already banished from the world long ago and can only act through intermediaries, and the concept that mortal activity actually can make a difference.
However, Middle Earth is not a specific allegory, certainly not the way that Narnia was.