Having studied Physics and science in general for years, being a Skeptical thinker, and knowing about formal systems, I do think that I KNOW what evidence is.
I have a book, "An Introduction to Scientific Research". There is nothing in there about accepting second, third, or fourth hand stories as evidence.
This is a representative statement of how some atheists approach historical reports. They use a "scientific" standard of evidence to evaluate historical reports. But there are obvious problems with that comparison:
i) Historical events are unrepeatable, whereas science often deals with repeatable kinds of events.
ii) But even on its own terms, scientists depend on testimonial evidence for most of what they believe. A physicist may have little firsthand knowledge of biology. He relies on the testimony of biologists.
Even within his own field, a scientist is dependent on testimonial evidence. A geologist relies on findings from the fieldwork of other geologists for his understanding of geology. A physicist doesn't personally duplicate every crucial experiment in physics. He relies on physics journals for much of what he believes. And so on and so forth.