Some of the best resources to use against Jesus Mythicism are not necessarily books that were written in response to this theory. One of the reasons for this is that most scholars have decided that the JMT is not worth responding to.
One book that I have read a couple of times is Structure and History in Greek Mythology and Ritual by Walter Burkert. This is a collection of essays on a number of different issues related to Greek myth.
This is not an introduction to or an overview of Greek myths. There are plenty of other books for that. This takes a bit of deeper dive, looking at some more specific questions.
There is plenty in this book that I think the general reader interested in Greek myths would enjoy. I found it interesting for my work on the Jesus Myth Theory for a couple of reasons.
The only one I will highlight here is that he responds to the influential work of James Frazier, especially his work on the “dying and rising gods.” I put that in quotes because Burkert demonstrates that most of those figures Frazier uses for that do not in fact fit that description.
If you are interested in learning more about Greek myths from a scholarly perspective but written in an accessible way, I recommend Structure and History in Greek Mythology and Ritual.
