I do not believe that everything happens for a reason. One might argue that atheists would chose not to believe that everything happens for a reason because logically it there was a reason it would indicate the presence of a diving or higher power/supreme being. I do not believe that there is a divine supreme being.
There are many things that happen in this world that has no meaning and no reason to happen. Rape for instance or miscarriages. The Indian Ocean tsunami of 2004, Hurricane Katrina and any other of the natural disasters. An innocent child being killed by a wild animal. Children dying due to neglectful parents/adults. Many, many other things.
The worst comment I hear during a natural disaster that claims many lives is – it’s god testing us! Fuck you and fuck your god. I never hear that coming from the victims. Anyone who has not been affected by the disaster can say such comments but it’s really stupid to say so.
I do believe that we alter or rather affects events by the decisions we make and mostly the outcome, atleast to a good extent. But not everything happens for a reason.