Well that is just a restatement of that old phrase "absence of evidence is not evidence of absence". And it is true, as far as it goes.
However - and its a big however - those people of faith from main religions who have us believe that god is omniscient, omnipotent; Can hear all prayers and will answer as they see fit, and that miracles are evidence of gods magnanimity. If that were so, then some evidence would actually exist; god would leave footprints and fingerprints all over the fabric of the universe - but there is nothing like that. No significant evidence beyond anecdote.
So in this instance, absence of evidence is indicative that no evidence actually exists- ergo, no god.
And this doomsday scenario you mention of Atheists vs God, the battle royale, the armageddon showdown that gets your juices flowing - doesn't really do anything for me, since I have seen nothing to suggest that your god exists! Its like threatening me with a rumble with a flying spaghetti monster, or a unicorn...