He questions whether atheism is a reason or a result of rebellion, and the saying that “An atheist cannot be Russian”. The result is a novel that compares favorably and provides an eloquent introduction to themes that will be dealt with at the family level in The Brothers Karamazov.
Liberalism and Socialism are contrasted by representative characters from two different generations. One is that of Herzen and the liberals, represented by Stepan Verkhovensky and others. While Stepan's son, Pyotr, is the reputed leader of the new generation of nihilist anarchists who are the precursors and somewhat participants in the rise of the Russian intelligentsia.
Demons does not only look forward, but also backward as can be seen in comparison with The Idiot which ends with Prince Myshkin in a Swiss Asylum; the silence of madness.
The Demons ends with the silence of suicide. (You have to read it to find out who, when, and why) The cabalists (the fivesome) are representatives of the central importance of ideology (nihilistic anarchism). The lives of the cabalists literally depend on the whims of their leader, Pyotr, and their own willingness to follow the ideology.
Through all of the novel there is in the background, Nikolai Stavrogin, son of Varvara Petrovna, spinning his web, better yet acting as a puppeteer while others speak and act for him and as his whim commands. Compared to The Underground Man, Stavrogin is relatively silent; he lets others speak for him: Pyotr, “you wrote the rules . . .); Shatov, “I was the pupil, you were the teacher”; Kirilov, “Go look at [Kirilov] now---he's your creation”.
The plot seems somewhat complex, but the organization can be seen more simply when one views the contrast between the two generations, Stepan and Varvara vs. Pyotr and Nikolai, and within that the detail maneuvering with the additional characters, especially the changing views within each generation and between the two.
Ultimately there is a coming together of characters and the ideas they represent in a sort of maelstrom of events at the end of Part Three of the novel. It concludes with an explosion of activity that is only hinted at in the long introduction in Part One. That is just one of the aspect of this novel that raises it to one of the best from the pen of Dostoevsky.