I've read a good deal of Gore Vidal's work, but only recently read his Messiah, though it was published in the 1950s and so has been available for reading for quite some time.  There are other works of his I haven't read.  I haven't read Myra Breckenridge, for example, or The City and the Pillar.  Perhaps I will some day.

I'm an admirer of Vidal the author, but not necessarily of Vidal the person or TV personality.  His personality doesn't intrude on the books I've read; that is to say, his personality as it appeared on TV talk shows of the past.  It can be a mistake, I think, for good writers to appear on such shows, as they're asked to participate in order to provoke and do so gladly, which I think diminishes them.

This particular novel describes the origin and "progress" of a religious movement based on the insight of a curiously charismatic former mortician's assistant that death is not just something we shouldn't fear, but something we should want.  The protagonist of the book is given some similarities to Vidal himself, as when he first begins his portrayal of the "messiah" in question and the way in which the movement developed, we find that at the time he met the man, he was involved in researching the Emperor Julian for purposes of writing about him.  Vidal of course wrote a novel about the emperor entitled, unsurprisingly, Julian, which was published ten years after Messiah.

For reasons not entirely clear, the message that death is desirable is enchanting to all who hear it; or, at least, all who hear it while seeing the one who speaks it, called John Cave in the novel.  People find it liberating as it extinguishes the fear of death.  Vidal or the Vidal figure, called Eugene Luther, is one of Cave's first converts though he is as might be expected a reluctant one.  Luther is aware of the fact that the claim that death isn't to be feared is not a new one, even in the form expressed by Cave, who thinks it to be an endless sleep, without any form of personal immortality.  It is in fact ancient, and one can see it in the works of Lucretius and the Stoics and Epicureans before him.  But wanting to die seems an odd premise for a religion.

Early in the book, it's hypothesized by Luther and others that Cave's remarkable appeal is the result of some kind of hypnosis.  Cave himself is portrayed as a simple and unassuming man, interested only in his rather narrow message, however; he doesn't seem at all intent on mesmerizing people or taking advantage of them in a sinister manner or indeed in any manner.

Cave and his message are taken up, though, by a publicist who milks the machinery of the media to its utmost in popularizing them both and broadcasting the message far and wide.   That machinery was formidable even in the 1950s.  Rich donors and converts appear, a corporation is formed.  Luther himself is retained to prepare a kind of introduction to Cave and his message, referencing and expounding on the philosophical basis for the message.  A kind of religious business is established.  The message spreads with great speed, throughout the world.  There is opposition from established religions, eventually there is violence against Cavism and the Cavites and ultimately violence by the them as they become well established and become the establishment, wielding political power to stamp out opposition.

The book is written as the recollections of Luther, who became a leader of a kind of heretical sect which thought the message death was not to be feared should be used to enhance life, not make death seem desirable and went into voluntary exile.  His writings which once formed the basis for the religion have been expunged.  The message is rewritten by those who didn't know the founder; the religion has become something different, something powerful, intolerant, oppressive, intent of saving and thereby dominating the world.

In researching the Emperor Julian, Vidal became quite knowledgeable about his attempt to restore paganism and eliminate the favors and status granted Christianity since the reign of Constantine.  He became aware of the manner in which Christianity became an institution over time and assimilated the Roman Empire, knew its holy books were written decades after Jesus lived, knew that other books regarding Jesus were proscribed, heresies were quashed, an orthodoxy established. 

I tend to think this satire by Vidal was primarily intended to reflect his views on what happened to Christianity, on the triumph of the Church rather than the message of Jesus which clearly appealed in a dramatic manner to many, but was over time changed, ignored, extinguished as deemed necessary by Christians when and after they accepted the "gift of Constantine" and gained the world while losing their souls.  There are too many parallels between the rise of Cavism and that of Christianity for me to think otherwise.  Another thoughtful book of Vidal the author, so much more admirable than Vidal the personality.