It should be easy to accept someone who says he does not believe in god. This is pretty basic tolerance. If an atheist asks a believer: What's the difference between your god and an imaginary god?...and the believer's answer is vague and/or nonsensical, then it's onbvious the believer doesn't have much clue what he's really talking about, so why should he get angry/frustrated with the atheist for exposing his weak arguments?