To say you “choose to believe” is not the same as saying you know as in I know that Christ is risen. Nor would atheists care a lot what Christians believed if Christians would keep their beliefs to themselves like followers of Thor and Wicca and other similar groups do. But Christians believe strongly in evangelizing the entire world and in enshrining their religious beliefs in the laws of the land, going so far as to force the rest of us to pray to your God before public meetings.
That’s like my Thor-worshipping friend demanding that before every public meeting Christians must participate in some sacrifice or oblation to the honour of Thor. As an atheist, I do not consider one more rational than the other but at least my Thorist friend will not evangelize; he keeps his beliefs to himself. So do I for the most part because the majority of Western society is Christian and Christians tend to ostracize atheists subtly or not so subtly.
BOTTOM LINE: If you don’t want atheists to talk religion with you, stop talking religion yourself when you are with them. I’m sure the atheists in your life will be relieved.
EDIT: As an atheist I refuse to say I “choose to believe in atheism” because it’s not true. It is true that education helped me better understand how the world worked; I learned the natural explanations for things God was supposed to do. Since I could see with my own eyes that this was true, it’s not “choosing to believe,” but accepting the facts as they exist.