I believe that the reason atheists and theists are unable to get along and agree on simple matters doesn't come from the belief (or non belief) of some higher being, but because of the misconceptions of every religion about one another. Because of so many stereotypes and misunderstandings in this world, today, it's nearly impossible to learn about a characteristic or fact about somebody and not judge them because of some stereotype one has previously heard. This doesn't even apply just to religions, it can apply to anything: hair color, job title, anything.
As a person who has experienced both being a theist and an atheist, I have been judged in both directions. Because of this, I have learned not to judge somebody because of their religious beliefs. We all have our ups and downs, and occasionally, I still catch myself judging others because of their religion, but I remember how I felt when I first told my parents that I wanted to stop going to church because I didn't want to do something that went against my own personal beliefs, whether it satisfied my friends and family, or not.
What many theists don't understand about atheists is that we are human beings, just as much as they are. Just because we don't believe in the existence of some higher power, doesn't mean we are intentionally reckless and disobey laws, or skip school and work. Atheists are just as honest, hard-working people as any theists are. We aren't going to raise our kids to be bad because there is no god to judge us. We try to live our lives as honest as possible, and try our hardest to do so. In school, atheists don't do any worse than theists do. As a college student, I currently have a 3.2, and I know of many atheists who have 4.0s or have failed. From observation, theists do no better nor worse regarding school or work performance than atheists do. Sundays to us, are just another day of the week. We don't curse everybody who pulls into the church parking lot (although with every religious group, there are many people who take their beliefs to an extreme), and we don't shun people who are dressed in their Sunday best when we see them at Target at 1 pm. We just try to live our lives just as much as any theist does.
On that note, atheists do a lot of judging, too. A common belief of atheists is that all theists blindly believe in an existence they can't see, hear, or feel. Whether this is true or not, isn't this something that everyone does on a daily basis? How many atheists believe in luck, peace, hope, trust, or love? It is not possible to see, hear or feel any of these things, yet to some people, they do exist. Sometimes, believing in something you don't necessarily know exists just feels right. Some of them know that they might just be wrong, but they trust in this higher power that they aren't. If believing in something is what makes somebody happy, why should anybody try to take that away from them?
If not believing in something is what make somebody happy, why should anybody force them to believe in anything?
Theists and atheists have a common goal: to be as happy as possible, to feel comfortable with their beliefs, and to live their life to the fullest of their capabilities. If this is true, why are we constantly going about trying to "convert" people? Not necessarily challenging people's beliefs, but literally trying to convert them?
Why not just state your opinion of the matter, and let the person decide for themselves?
NOTE: I do realize how naive I sound. Maybe I'm just too hopeful.