Why does everyone hate on me for being an atheist?

Okay so I made my descion a while ago and I guess I didn't know my sister was more religious then I thought so she told my parents and then my parents went to church without me and it was there turn in the cofession box so I guess they told the paster or whatever and now I get all this hate mail say god hates you he will avenge his name ect. And people in cars drive by and call me god hater I think it's getting out of hand why is that its my choice who are they to judge