The main theme might be about the journey of the 'child of god' character, perhaps exploring identity, faith, and their place in the world.
In many novels with such a title, the main theme often delves into the relationship between the 'child of god' and the other characters or the world around them. It may look at how the character is different from others due to their special status. It could also explore the concept of destiny and how the 'child of god' is fated to achieve certain things, whether it's to save a community, bring about a change in the world view, or something else entirely. It might also examine the internal struggle of the character as they balance their divine nature with their human-like experiences and emotions.