Yes, but such requires justifying the NT which is beyond the discussion in this thread and beyond what I'm willing to get into in this context.
Nope. That's not what we are saying.
Logic comes after one agrees to what is revelation. We can't move onto step two before step one.
Why would you say that? They are exclusively one, alone in being.
There is only one YHWH. There are three who are the one, alone, singular, exclusive God, YHWH.
They argue the same thing of your side. Maybe you should focus on the logic of the trinity so we can make some progress?
Up to you.
There is nothing to argue about. That sinners rebel against the truth isn't a reason to think the NT isn't conclusive. There is no logical issues with the Trinity; just those assuming axioms as to deny the Trinity.