Overall, I appreciate the post and agree with most of it. It's just brain exercise for the most part, but I do enjoy philosophy of religion and logic in particular. It's enjoyable. And nice to use my liberal arts education once in awhile.
Regarding your first paragraph, I would replace "assumptions" with "premises" and then say, "it depends." For example, it depends on whether we can both agree that a premise is true. It's just how arguments are built.
So, for example, I misquoted St. Anselm before... I think I attributed to Thomas Aquinas. Anyway, I love the language involved in that argument. The entire thing builds on agreement on definitions (from memory, so it is paraphrased from the original):
- God is that than which no greater can be conceived.
- If God is all power, all knowing, and all good, but doesn't exist, than we can conceive of something greater... a being that is all of those things... but DOES exist.
- Bingo, bango, bongo, God must exist.
This argument only works if we agree that the definition of God is quite literally THE best, most amazing, powerful, awesome thing we can possibly imagine.
So, in the same way, when you think about the problem of evil, and start to consider how theists define their own god (core elements, without which it isn't the theistic god), you run across things like omniscience and omnipotence. Point is, we can start to argue that god doesn't exist by agreeing on things that, without which, it would not be God. It might be something pretty cool, but not god. Like it's very powerful, but not all powerful... dangerous, cool... but can't be God, because God is all powerful (that than which no greater can be conceived).
Interesting aside, not all theists have agreed on whether God is benevolent... for example, many of the founding fathers of America were deists.
In other news, I realize this is completely off topic, but I dig this ****. I understand if we need to get back on track.