Evidence is the stuff of science.
Some may be surprised that science does not really deal in proof, but in evidence. (OK, maybe alcohol and maths deal in proof.)
If the police find a fingerprint at the scene of a crime, many would say that was "proof" the suspect was there - but both the police and the scientific community would say that it was evidence. A second person having a finger print that is indistinguishable from the suspect's print is highly improbable but not impossible. Also the suspect’s fingerprint may have been taken to the place to incriminate him/her.
Evidence and Atheists
The question of evidence is very important to most atheists - because that is what they need before they accept that anything is true. Rationalist atheist do accept as "true" statements for which there is evidence. The simple lack of evidence for anything supernatural is what drives most atheists to question religions. Typically atheists are then accused of being many bad things; of disrespecting other people's beliefs, of believing they know everything and of arrogance.
Some might argue that believers who accuse atheists of these things are themselves guilty to some form of intellectual arrogance, as all atheists are really saying is, "Show us the evidence."