Mary Shelley's novel Frankenstein illuminates the problems which can arise when mankind tries to be a god (or God--from the Christian perspective). In this novel, Victor Frankenstein, the protagonist, proves to have the God-Complex.
First, Victor brings the dead back to life. While he does not bring one single human back to life, he does use multiple parts of different humans to create a new being (noted by the use of "bodies" in the following quote).
Darkness had no effect upon my fancy, and a churchyard was to me merely the receptacle of bodies deprived of life. (Chapter 4)
Secondly, Victor has created a new Adam (this idea is illustrated when the Creature states that he feels like Adam--after he completes reading Paradise Lost: "Like Adam, I was apparently united by no link to any other being in existence"- Chapter 12). God, according to Christian ideology, was the first to create life (thus showing Victor's own likeness to God).
Thirdly, Victor feels as if he should feel the gratitude that no other human could ever feel based upon his creation of a new life.
Life and death appeared to me ideal bounds, which I should first break through, and pour a torrent of light into our dark world. A new species would bless me as its creator and source; many happy and excellent natures would owe their being to me. (Chapter 4)
These quotes illustrate Victor's likeness to God given he is naming himself as one who can bring a "new species" to the earth.
Essentially, Victor raises himself up above all others in mankind. He, then, unlike mankind, proves to believe himself to be like God.
Although Mary Shelley was not particularly religious, she was writing within a culture that was deeply embedded within Christian thought. Her own social milieu was also very interested in the ancient Greek gods, albeit from a literary, rather than religious, perspective.
The first godlike feature of Victor is that he shares with the God of Genesis the act of creating a creature in his own image. In a sense, we can say that the monster is to Victor as human beings are to God.
The next parallel we see is in Victor's relationship to knowledge. In Genesis, humans are forbidden to eat the fruit of the Tree of Knowledge, as there are certain types of knowledge that are proper to God but not mortals. In trying to attain knowledge, humans are attempting to become godlike in a way that ends badly (the expulsion of Adam and Eve from Eden, for example); Victor is also shown as a character whose quest for knowledge beyond what is proper can be understood as a failed attempt to emulate God.
Finally, the very title of the book suggests that Victor is like the Greek god Prometheus who brings humans the gift of fire. In the works of Aeschylus, Prometheus also brings humans the civilized arts and knowledge. Victor, however, unlike Prometheus, has a failure of courage and does not care for his creation in the way that the original Prometheus cared for humans.