It is made up of three essays: "Nature" and the "Utility of Religion", were both written between 1850 and 1858, while "Theism" was composed between 1868 and 1870.

[1] The book is critical of traditional religious views, instead advocating for a "religion of humanity".

[2] In this essay, Mill argues against the idea that the morality of an action can be judged by whether it is natural or unnatural.

Despite this, Mill is suspicious of people taking advantage of those who seek to survive their deaths.

[4] In the book's final essay, Mill explores a number of arguments for the existence of God, using a methodology based on evidence.