There is one and only one thing an atheist is concerned with and that is the existence of a God or gods. Calling me a god does not change that fact. If you are asserting the universe did not exist prior to my existence, you are making an assertion that goes against all we know and have learned about our existence and the existence of the surrounding universe. I’m sorry, but I am going to need a little more than “What if I said?”
You can make any claim you like. Truth is that which comports with reality. I can call a paper cup a god and it does not make it so. People have called all sorts of things Gods; crocodiles, turtles, tigers, and even other people. I can think of several people on the planet now who hold themselves to be gods. Kim, Jong-un, Sergei Anatolyevitch Torop, José Luis de Jesús, and more.
Perhaps I could be the Hindu version of God. Just one element of God playing hide and seek from itself? Still, without evidence. Without something substantiating the claim, all you have is an unfalsifiable fairy tale. Something made up in the minds of men. Something that can not be justified in any way at all. Something that will join the other hundreds of thousands of mythical beliefs humans hold and once held to be true.
You are correct. I think therefore I am… But it runs deeper. You are what you believe. Choose your beliefs wisely. You can be a God if you want to. I have a hard enough time just trying to be a human.
EDIT: When I look at the people in this world who are or were gods, I am completely unimpressed. From Jesus copying Orion, Inanna, and Dionysus, to the three magical flood stories. From Josep Smith meeting Angels in America to Muhamad meeting them in a cave in Mt. Hira. And for God’s sake, let’s not leave out Lord Xenu! You believe what you want to believe. I’ll wait for the evidence.