Are you suggesting that there is no Messiah? Why would an "anonymous" author choose to ridicule such a concept?
Perhaps we should think about the motives that people have for the books they write.
After all, it was not as easy to write a book back in those days!
To do so, one would have to have quite a deeply ingrained motive for doing so. I see two basic passions and motives as being possible.
1) The "anonymous author wished to share the impartation that he/she received by the Spirit of the living Christ
2) The author was dead set against any rival religions to his/her own mindset and sought to ridicule the new cult of christianity, (as they saw it)
Either way, we could conclude that the anonymous authors were serious.