Frankenstein provides for a spiritual conflict in two ways. First, Victor is analogous to God. One of the prevalent themes explores the consequences of "playing God." Surely, Victor has created a man in his own image from discarded parts of dead bodies, or "dust". He then makes wild decisions as to the use of science for purposes beyond the human realm.
Next, the creature, in his portion of the story, relates being influenced by "Paradise Lost" and considers himself first as Adam, a man without a race or culture or history. Later, the creature considers himself more Satan, a demon tossed away from the love of God forever. He has been cast out of heaven and forced to wander alone, just like the creature. Of course, the creature is not the devil, but his capacity to become evil grows each day.
The novel seems to suggest that life without God is tumultous at best, but that human beings should never attempt to do what is in the realm of only God.