Do you think that Coupland assumes that the majority of his readers ARE stabilized to begin with? It seems to me that his destabilizing style is actually comforting to the destabilized generation(s) that form his intended audience. The intensely questioning nature of his writing is very familiar to those who have grown up in an increasingly confused world, where a generation gap occurs every 5 years and we are constantly flooded with information that changes our ability to place ourselves in a constant narrative.
This is certainly a provocative point: Coupland's generation "X" (my own generation) is more stable than your generation, "Y," and so what looks like a destabilising book to Gen. X will simply be life to Gen. Y.
For lecture purposes, however, I will cut the Gordian Knot, and say that the uncertainty and instability is the characteristic of Life after God and will ask you to identify and understand the specific literary aspects of that characteristic: the status of the narrator, for example, the presence of existential Fear, etc.