Humanity
As told by the title, man is one of the main characters of this work of opinion, as he is the main subject of the novel. Throughout all of history, Chesterton says, man has persisted and has had great mental reason all along the way. This is why he calls the race "Everlasting", because we have persisted, and we have persisted above our less intelligent animal counterparts.
Humanity, Chesterton says, did evolve in some ways. The physical form of the human changed over time, but he says that the level of reason they had did not. From the beginning, there was a mystical sense of reason that had to have been given to humans by some other being, because that sort of reason could not have been evolved out of another animal. Chesterton argues that humanity is right in believing in religion, and it was not simply a coincidence that they developed the practice.
Religion
Religion plays a large part in the book, because its beliefs and origins are both debated and evaluated. One thing that Chesterton says of Christianity is that it was indeed not around since the beginning of time. He agrees that other religions came before, but Christianity was simply the religion that was correct and that humanity was looking for all along. Religion is seen by Chesterton as something vital to survival, in that it influences every aspect of human life in some way or another.
