Christianity does not have a clear and unambiguous definition. Rather, I see Christianity as an umbrella term that includes a variety of multiple branches, with many shared beliefs, but also not exempt of notable points of disagreement. In some cases, the disagreements have been so extreme that they have led to major divisions within the Church. I'm totally aware of this fact and, therefore, I do not seek arguments for individual branches. Instead, I'm interested in the main arguments used to defend the veracity of several core beliefs of Christianity, shared by the majority of Christendom, which are specific enough to distinguish Christianity from other religions.
To the best of my knowledge, the following are core beliefs of Christianity that are accepted as true by the vast majority of Christians:
- Monotheism: there is one God, who created the universe.
- There is a spirit realm beyond the physical.
- Miracles are possible (or at least are believed to have occurred in the past).
- Angels exist.
- Satan exists, demons exist, and the world is (and has been) heavily under their influence.
- There is an ongoing spiritual battle for the eternal destiny of each human soul (eternal salvation vs eternal damnation).
- The Bible was inspired by God.
- The resurrection of Jesus was a historical fact.
I'm not sure if there are other core beliefs that I'm missing, or if the beliefs listed above should be reworded to be more accurate (if so, please let me know in the comments). That said, I think that these eight core beliefs are sufficient, in the sense that if they are proven to be true, they together would create a very compelling case for the veracity of Christianity over any other religion.
I quickly searched the literature for examples of what apologists usually argue for and noticed that most apologists tend to focus on beliefs #1 (Monotheism: there is one God, who created the universe) and #8 (The resurrection of Jesus was a historical fact). This makes sense, because the former makes the case for monotheistic theism in general, whereas the latter complements by making the case for Christianity specifically.
That said, point #5 (Satan exists, demons exist, and the world is (and has been) heavily under their influence) is definitely a core belief of Christianity too. Satan is all over the place in the Bible, from Genesis to Revelation. Jesus casted demons out of people left and right during his ministry, according to the four gospels. The fact that the Scriptures teach about the existence of Satan and his minions is overwhelmingly clear and undeniable, to the point that I'm not sure if it is even possible to be a Christian and not believe in the existence of Satan and his army of demons.
Question: Has any Christian Apologist ever published arguments for the existence of Satan, demons and their ongoing influence over human matters?