As an American, I honestly haven't run into this. I am religious, and most of my coworkers are religious, but we have had an atheist and an agnostic in our group (we're all developers) and it really didn't seem to matter. Religion rarely comes up in a professional setting, and it didn't come up when we did things outside of work as friends.
As long as you aren't aggressive against that which you don't believe, there really shouldn't be any problems. Most of the problems I run into are from atheists and agnostics picking a fight with theists. Treat others with respect and you'll get it in return.
Treat others with respect? Do atheists get any respect from the religious? From our own government? Is it respectful to get religion (theistic or not) and god shoved down my throat everywhere I turn?
If you haven't noticed, there's a war against christianity in the US. Nativity scenes being shut down. Not being able to pray in school. The constant attacks from popular culture and the media. Atheists tend to be especially vocal about the fact that they shouldn't have to see, think or hear anything even tangentially related to Christianity (although they have no problem with Islam. Go figure.) Christians see this as an attack on their ability to practice their religion.
Christians in America are however attacking abortion rights. They also attack marriage rights, gay rights, transgender rights, help for the poor, human rights, and basically everything that Jesus was for. To claim that the majority of Americans are practicing anything Jesus stood for is quite frankly silly. No one has said kids can't pray in school, what's been said is that you can't force prayer in school unless it's a religious school,in which case religion rules.
This silly "Attack on Christianity" ginned up by Fox News and the religious right is absurd in a country where the vast majority of the country proclaims to be Christian.