It is simply not truthful to claim these people are not against God. They are, and rudely so. They are intolerant of any Christians expressing their beliefs, while demanding the right to shout theirs loudly from the rooftops, and that we respect theirs. They proselytize, they preach their religion to our kids in school. It is possible to be good without God, but many of them, preach that there is no goodness in Christians, make claims that we are responsible for the evils of the world. They are as full of hatred and bigotry as any Klukker, and there is nothing good about such people, IMHO.
I'm not against something I don't have belief in. While I choose to live my life quietly and keep my (non)religious beliefs to myself, some athiests do not. A good majority of theists and atheists alike keep their opinions to themselves, but the ones who do not spread different messages.
The Atheist leaves a reassuring message to those who may be on a crooked path between believing or not, to let them know they can live a good, wholesome life without a belief in a god.
Have you ever read a religious billboard before? Accept Christ or go to Hell!
And you're the one outraged about a sign saying it's ok to be nice!
We don't want our faithless religion in schools, but we do want yours out. It might be your job as a religious man to spread your faith, but please don't do it to the highly impressionable children of others. Please do fill them in on the evil, tyranny, and death the wars and violence your religions have brought to this world in history class, however, because that is truth. Wait, we don't do that, because that would be against the Christian agenda.