“The only thing you can say about all atheists is that they all lack belief in gods.”
There are many atheists around the world who don't embrace your carefully worded modern definition. They simply say "I believe that there is no God." Your cut-and-paste movement only started a few years ago. But you are still connected to the old “I believe” atheists. If I have a car and say “I lack belief in makers,” it means I believe that cars have no makers—and my car therefore had no maker. It means that I believe that nothing made it. So, carefully worded though your modern definition may be, it still leaves you believing the scientifically impossible—that nothing made everything.