I don’t get this dalliance into Satan* having the ability to beat God. Where do you get this information? The only book that deals with the “final battle” is Revelation, which is presented as Jesus telling John what’s going to happen in the future. And, in it, God wins, even after giving Satan quite a few chances.
But, if you want to get into how Satan fits, you need to take a look at Job, where you can clearly see that Satan is subservient to God. He has to ask God for permission to do anything. He is presented almost the same as an angel, which I assume are the “demigods” you referred to.
The Trinity is definitely more difficult. It is presented as being inherently confusing, if not downright contradictory. The whole concept is that, what appears to be three different gods working together is really one God who exists in three persons. I don’t believe there is any official explanation of how this is possible.
But I wonder what happens if we look at the original text, the Athanasian Creed The word used for person is persōna. It originally meant a mask that actors wore in plays (ala the Greek traditional play), but was extended to the character themselves, and finally to the character on the stage of life i.e., the individual.
I propose that, when it was originally written, persōna referred to the personality one presented to the world, i.e. one’s mask or character. Taking this into account, one could see the “three persons” not as God himself, but how he presents himself to humanity. None of these are untrue, but just not Him in His full glory (which, if you’ll remember back in the Torah, God can’t reveal to humans without killing them). This is backed up by the oft used version of God having three “manifestations” rather than persons.
I offer this version as being an alternative to the incoherent interpretation most offered today. We can easily picture one person with three different personalities. However, unlike humans, God, being omnipresent, can be in multiple places at once, so His three personalities can exist simultaneously, and have since the beginning. (This is not Modalism, where we only perceive Him in this manner due to our limited capacity as humans.)
When interpreting the text in this view, I see no discrepancies, despite the fact that it could have been made much clearer. But, as has been pointed out above, Christianity seems to enjoy its “mysteries.”
*As far as I can tell, “Satan” and “the devil” are considered synonymous, especially in the New Testament, and definitely by most Christians today.
