I would rewrite your first sentence as, "An invariant sentiment from skeptics and critical thinkers is that they wont believe any claim absent demonstration of sufficient supporting evidence."
Semantic quibble: I believe that electromagnetism exists, but I don't believe in it. I reserve the phrase believe in for faith-based beliefs, not sufficiently evidenced beliefs. This may illustrate the difference between believing and believing in, although he isn't using that language. I would have written that first sentence, "Truth doesn't need to be believed in":
"Truth does not demand belief. Scientists do not join hands every Sunday, singing, yes, gravity is real! I will have faith! I will be strong! I believe in my heart that what goes up, up, up must come down, down. down. Amen! If they did, we would think they were pretty insecure about it." -Dan Barker
Electromagnetism is posited to be the force that pulls compass needles, allows balloons to stick to the wall, and makes the night sky light up with bolts of lightning. It took the genius of Maxwell to realize that electricity, magnetism, and light were all manifestations of a single force. Nothing else accounts for any of this unless we want to invoke spirits, and adding spirits to the math and science does nothing for the science's explanatory or predictive power. This is the fundamental difference between something like the electromagnetic force and gods. We need the former to account for observation, but not the latter. Think about it: a science of the force electromagnetism with no gods, a religion of electromagnetism that postulates unseen agents with no science or math, and both combined - a physical theory with a deity thrown in. It should be apparent what's different between scientific beliefs and faith-based beliefs
What I find odd is couching that in the language of an emotion, hostility. What you are observing is people who have a different standard for belief than the theist, people who reject faith for themselves. Ask yourself why you chose that word, hostile. Nobody here has been hostile to you. They've been like me - unemotional.
What justifies calling rejection of an idea hostility for you? I have a tentative answer - an educated guess - but I'll wait to see yours.
I have a definition for gods - supernatural, sentient agents capable of building universes. If you ask me, an agnostic atheist, if I believe such a thing exists, my answer would be no, because I don't have a reason to believe that absent some finding much better explained by a supernatural intelligent designer than a naturalistic process. The critical thinker builds his world view the same way science does. His narrative evolves as new discoveries not adequately explained by the existing paradigm appear.
Falsify evolution, and I will be forced to believe that deceptive intelligent designers exist or existed to account for there being so much evidence for evolution, and yet the theory is incorrect, but not before. Even then, I would have no need to add supernaturalism into my new paradigm, which also can be explained naturalistically as the work of powerful race of aliens that arose through abiogenesis and biological evolution.
That description fits you. You don't know what you DO believe in. You can't describe it clearly. You don't know where it is or what it is. But you are correct: I don't believe whatever-it-is that YOU believe if it involves the supernatural.
