Decoste's argument is mostly persuasive. His chapters on how Suttree and Child of God implicate the main characters in a dehumanizing mercantilism were exceptional. Decoste expertly draws out how, for McCarthy, (Enlightenment) material and historical forces have deleterious effects on our character, sense of the world, our love of neighbor, and how we orient ourselves toward the world outside of us. McCarthy's often macabre literature, then, like O'Connors', is a shock to the system, a shock to all of us who've been insulated to the world around us (along the lines of Taylor's buffered self).
However, I'm not sure his argument accounts for the type of transcendent realities gestured toward in Suttree, All The Pretty Horses, or The Crossing, which are all decidedly not Catholic. I do not think McCarthy thinks there is a metaphysical substructure of "The Good" to reality. Nor do I think that is what is presented in his work. It also seems to me like not invoking and/or integrating McCarty's linguistic interests with the nature of theological language advocated for in the Catholic tradition renders this exploration a tad incomplete.