Why do theists call atheists as weak-minded people and vice-versa ?

I do think some atheists are weak-minded because some of them act like they are so smart and mature and yet they are hunting down theists just to mock them. That's very childish. A lot of atheists are very smart and some of them are my friends. There are some atheists who will agree to disagree and there are some theists who will do the same. The rest of them that are childish clash with the extreme theists who don't know when to stop. Those theists are weak minded.