That is not the definition of a god. They do not have to be unstoppable. Many pagan gods seem vastly inferior to freaking superman. And yes, he isn't a god. At least not by Naruto world standards. Hashirama and Hiruzen aren't gods either. It's just a title showing them respect for there great power. And when you version of a god is the Juubi, you are bound to have low standards for what you'd consider godly power.