You have a false sense of grandeur. You have not demonstrated why my argument is false. You have simply asserted that it is and then claimed without evidence that anyone who has taken a 101 logic course knows your right. However there are plenty which i am sure are better skilled at logic than you that would agree with my argument and the 5 ways of Aquinas which you believe to be false. So i don’t see the relevance of making that assertion. You are just telling me what you would like to be true.
It’s not about grandeur, just knowledge. Nothing to be proud about. -shrug-
Your argument can’t be false. It can be invalid, and it is. But, no matter.
Since God’s potential state to create was actualized (as any theist will say), God changed “by definition” (there are other examples if this one isn’t suitable). You couldn’t disagree with this on the basis of your argument either; because, your argument (as currently stated) specifies nothing which could resist my point here. So, you could only avoid this by introducing new distinctions. (even then, I don’t think you could)
(6) informs us that if anything is a thing that changes, then it is a member of the sum of all changing things: the universe. Since God is a thing which changes, apparently, he’s a member of the universe.
In (8) you say “none of it can be said to be the sufficient cause of its change.” which is another way of saying ‘no member of the universe is the sufficient cause of the universe’s change.’ Since God is a member of the universe, (8) informs us that he’s not the sufficient cause of the relevant change.
At this point we’re not warranted by your premises in concluding that there is or must be such a sufficient cause. You’ve not proffered any causal principle which compels us to do so. Your causal principle actually pops up in the conclusion: “no change can exist without an actual reality as its predetermining basis”. But, let’s just assume it was in a premise.
Then there must be an actual reality as God’s predetermining basis. etc. there are all sorts of absurd conclusions we could deduce here.