Atheists allege that Christian theology is unfalsifiable, unlike scientific theorizing, which, because it's fact-based rather than faith-based, is not only falsifiable, but according to Carl Sagan, "self-correcting."
Here's an example of self-correcting science:
During a talk at the Kavli Institute for Theoretical Physics at the University of California, Santa Barbara, Nima Arkani-Hamed, a physicist at the Institute for Advanced Study in Princeton, N.J., paced to and fro in front of the blackboard, addressing a packed room about the future of supersymmetry. What if supersymmetry is not found at the LHC, he asked, before answering his own question: then we will make new supersymmetry models that put the superpartners just beyond the reach of the experiments. But wouldn’t that mean that we would be changing our story? That’s okay; theorists don’t need to be consistent—only their theories do.