You're missing the point when you say guy with a capital G you're talking about the one above all. The beginning and the end the Alpha and Omega no limitations. Fiction or nonfiction. Not being antagonistic. Stating the obvious
For clarification, when we are referring to the being Harry calls the Almighty, Michael calls the Lord and Uriel might call the boss (tbh, we haven't heard what Uriel calls him) - on the forums we refer to that being as The White God (TWG as an abbreviation). This stems from beings like the Leansidhe calling that being The White God. We also do this because we don't want to confuse the other members of the forum with who we are talking about. TWG is the fictional being, calling him anything else (like capital G "God") could/would confuse this. It's just a formality but it helps keep the discussion on point. It also allows us to respect other members of the forum who do not believe in a god, God or have their own God like Allah or Yahweh that they worship. This forum is broad and has people from many backgrounds, cultures and faiths. Many also do not believe at all in the supernatural, and some I imagine are agnostic. If you read the section in the forum rules about Touchy Topics, this is skirting it. So if you want to refer to the character in the Dresden Files, please use TWG or The White God. When referring to the being that is the object of real world people's faith, by all means say God or Allah or whatever seems best.
Your point, as I understand it, is that because The White God has been inspired strongly by the Christian faith and the Christian literature they therefore must be the same. It's an easy and understandable mistake. Jim has clarified this as far as he is willing to. That is, TWG looks like what people in the Dresdenverse expect him to. To Muslim's he is Allah, to Jewish people he is Yahweh, and to Christians he is the Almighty. But he is far beyond this. Jim used the lesson about how three blind men find an elephant and one grabs the tail, one grabs the leg, and one grabs the trunk. To the first blind man the creature is thin and ropey like a tail, to the second the creature is thick and powerful like a leg, and to the third one he is sinewy and strong like a trunk. They are all right, yet all wrong. They have an incomplete picture of the creature. So using that metaphor we can understand that each faith in the Dresden Files gets only a partial amount right about the universe but gets other bits very wrong as they each don't have all the information.
How Jim refers to this being has no bearing on the real world, and nor does how I do. I'm not sure why you are so bothered about this but I hope you understand what I am saying here. Christians and other monotheistic religions believe that there is only one god, their god. They also then denounce any other being from another faith that is worshipped as a god as a false being or even a demon. However Christianity is far from the oldest religions, and polytheism is far older, and I doubt that people who for example worshipped the Egyptian pantheon of gods were less sure of their faith, and believed their gods to be just as powerful and unknowable as anyone else. So referring to those beings as Gods with a capital makes no difference at all, no matter how much any monotheist may wish it to be, especially as we are talking about the Dresdenverse and not our world. It might be appropriate when looking at it from Michael, Charity or Father Forthill's perspective. But not from Butters or Sanya (Butter's being Jewish and Sanya being agnostic). They serve the same being as Michael. There is no indication of which of the three is more right as it's very much about perspective.
Also, we actually don't yet know the hierarchy of the beings of the series, we have limited information from both the books and Jim's interviews. There could well be beings above TWG. TWG could be an Old One. We just don't have enough information. So just because Christians in the Dresden Files believe their god to be above all others, doesn't necessarily make it so. As for general usage, I think we're now in Touchy Topics area fully and I am going to leave it at that.
This whole section of the forum is dedicated to discussing the big reveals in the books, and inevitably involves a lot of discussion and theorizing around topics like this one - where there isn't enough information and we have to fill in the blanks. Sometimes it gets wild but its a place to have fun and people here by and large seem to. I invite you to try not and be so worried about this stuff - get in and enjoy it. If you disagree with someone try and lay out your argument as logically and fairly as you can.
You might not have felt you were being antagonistic, but saying you're laughing at someone else's post is baiting - especially if you're not laughing with them. As is being passive aggressive. I will say god, or God, as I see fit and seems appropriate to the context. I won't change it to appease someone who won't engage respectfully, or because you're merely upset. If you are genuinely offended by this, you are welcome to ignore my posts or you can ask politely for me or others to change something. But asking in such a hostile fashion will not get you what you want and will alienate most people.