Jared Diamond's book "The World Until Yesterday" (https://www.amazon.com/World-Until-Yesterday-Traditional-Societies/dp/0143124404/ref=asap_bc?ie=UTF8 has an excellent chapter on religion in relation to its role in human cultural development.
In that chapter he drops the idea that the success of Christianity results from its concept of forgiveness. In traditional societies that don't employ forgiveness, individuals the carry extra burden of looking over their shoulders for vengeance actions. Forgiveness might play an important role in getting over past "trespasses" and expanding a more inclusive and supportive society.
Here is a link to a good summary of the development of the forgiveness concept: http://ndpr.nd.edu/news/24656-before-forgiveness-the-origin-of-a-moral-idea/
It is particularly Interesting that this explanation based on forgiveness gets beyond concepts of virgin birth (https://en.wikipedia.org/wiki/Miraculous_births) and resurrection (https://en.wikipedia.org/wiki/Osiris) that are found in other belief systems such as Ancient Egyptian.