You did not understand what i meant.
You were claiming that atheism is a religion (and that agnosticism is the logical scientific position) because the non-existence of god "outside our universe" was untestable. That's precisely the fallacy that the "Russell's teapot" argument addresses.
Contrary to the popular aphorism, Absence of evidence is evidence of absence. It may not be proof of absence, but unless its outweighed by evidence of presence, then it's a pretty strong hint as to what the "null hypothesis" should be.
If something is inside the universe we can interact with it. If we cant interact with something, then it is outside our space-time.
Now there's an untestable assertion! If there was something "inside the universe" that we could not interact with, how could you know that it was there? The only way out of that is to take "that which we can interact with" as the definition of "Universe" - so "branes" and any other hypothetical phenomenon that might have interacted with us by influencing the outcome of the big bang are all part of the Universe. If god was sitting somewhere rolling an infinite number of 12-dice to pick the values of the fundamental constants then he's part of the universe. Choose a different word for "Universe" if it makes you feel better.
By that definition, If something "outside the universe" can't interact with us at all - if we can't even deduce its existence indirectly or use it to make some other testable prediction using current or future science - then its existence isn't just non-testable, it doesn't exist (that's really just re-stating the definition of "universe").