The book is largely concerned to rebut Dawkins and Hitchens; there are many polemical thrusts against a narrow bourgeois version of rationality, and a faith in Progress that thinks it is just enlightened neutrality. This is all good stuff, but what I find really interesting is Eagleton's thoughts on revolution and Christianity.
He is of course sympathetic to Jesus's message of the kingdom of God, in which the poor will finally have justice. But he resists the normal Marxist response: that instead of fetishising the dead Jesus, we must do what Jesus failed to do. Instead he argues that the myth of Christ's death and resurrection is no escapist illusion: Jesus's "death and descent into hell is a voyage into madness, terror, absurdity, and self-dispossession, since only a revolution that cuts that deep can answer to our dismal condition." This is the sort of revolution that a normal Marxist would angrily dismiss as illusory, for "our dismal condition" can be politically mended. For Eagleton, the idea of the Fall cannot be brushed aside. This is confirmed later on, when he notes that Dawkins and Hitchens "have no use for such embarrassingly old-fashioned ideas as depravity and redemption. Even after Auschwitz there is nothing in their view to be redeemed from."
Typical doctrinaire Marxism, however, usually doesn't have Marx's respect for bourgeois culture, and Marx's understanding of Christianity as an ideological framework. Later Marxists, most especially Ernst Bloch, shared Marx's respect for the accomplishments of bourgeois society even as they understood capitalism's devastating impact on the working class. Bloch set aside early 20th century Marxism's dismissal of "religion", and expanded a Marxist appreciation for the potential revolutionary power of Christianity.
An attack on Dawkins and Hitchens, whether from a Christian or Marxist perspective (or some combination thereof), is all to the good, especially as Eagleton cuts through much of the typical apologetic frew-frew and gets to one of the hearts of their very limited vision (at least, Hobson makes it sound that way). In any event, an expanded appreciation for the deepest content of the Christian faith, whether or not Eagleton himself "comes out" (as Hobson ironically put it) as a Christian, would be a nice read, indeed.