I've generally connected Atheism with open-mindedness.
This isn't always the case.
A bigot (in modern usage) is a prejudiced person who is intolerant of any opinions differing from their own or intolerant of people of different ethnicity, race, or class.
Most bigots lean on bits and pieces of religion in order to validate themselves.
Do you think that there is such a thing as an Atheist bigot?
Have you met one? Are you one?