Often when talking to religious people, most commonly Christians, I've been called out on various phrases that denote religious principles or beliefs to which I, as an atheist, do not adhere. To avoid future confusion, I've decided to put together a brief Atheist to Christian translation guide for terms that could be mistaken for secret theism.
The core atheist principle is that we have been given no rational reason or empirical evidence for the existence of God, so it's not that we actively disbelieve in a believable premise, we just don't believe in that same way we don't believe in unicorns and pots of gold under rainbows. Yet we use God, Christ, and Jesus in many phrases, for instance, "Thank God." However, we are not actually thanking God when we say this, we are merely expressing relief that something bad, or merely worse, did not happen, through no effort of our own. We use God as a metaphor for the things in life beyond our control, which is what you do too, you just have an anthropomorphic representation of the concept.
Most commonly misunderstood when used in the phrases "He got soul" and "Will Ferrell has no soul." Atheists explicitly do not belief in an immaterial component of the human condition responsible for his or her personality, personableness, or musical prowess. We do believe that the average person cannot calculate all the subliminal physical, hormonal, pheromonal, and cultural cues that are responsible for his or her reaction to any other given human. More importantly, "his natural-seeming demeanor and well-fitting clothes underscore his relaxed sense of humor and pleasing aroma, all of which suggests to me that he is, to the best of his abilities, trying to be honest and friendly, while his body language, non-aggressive eye contact, and the content of his conversation allow me to infer a complex but socially acceptable worldview, as well as what I've come to refer to as wisdom" is just an ungainly thing to have to say. "He got soul" saves syllables, and "soul" in general sums up all the things we can't be bothered to figure out or explain in casual conversation.
In any use of Hell, we're really just borrowing the term to encompass a worst-case scenario. "War is hell," for instance refers to our belief that war is extremely unpleasant, to the point where we'd rather it didn't exist at all. Like Hell doesn't exist.
Trust me on this: atheists as a whole would really, really love to know that there is a perfect, unearthly place where we are unconditionally loved and in a state of perfect bliss without fear or end. Since we're reasonably sure there is no such place, we get what we can from chocolate, wine, and sex, all of which provide a temporary reprieve from the fact that we are fragile monkeys headed toward a dusty finale. Anything that relieves the existential dread stemming from this reality can be described as heaven. The only real difference between your heaven and ours is that you might get yours if you're right about an extremely unlikely theory, while we get ours pretty much whenever we want.
Cultural meme. We don't actually think your soul has left your body through your nose and you need the temporary attention of God to prevent demons from entering you body while your soul gets its bearings. Honestly, you shouldn't believe this even if you believe in the component demons, God, and soul. I mean, really?
"What would Jesus do?"
We're still on the fence about whether or not we believe Jesus existed at all. We don't use this phrase as an invitation to meditate upon the motivations of your Lord and Savior, we're really just calling you on your bullshit. Since we know you'll come up with all kinds of excuses to take away people's rights and kill them if they complain about it, throwing out the name of the fundamental Christian symbol of love loosely translates to "Shut the fuck up, you flaming hypocrite."
There are many things it is possible to believe in. The atheist will use this phrase to suggest one should continue to believe in some concept or person in which one has in the past been inclined to believe. The difference is that the object of belief has in theory had a record that perhaps doesn't deserve to be shaken by a moment of doubt. Of course, any good atheist must accept a portion of doubt along with any concept or belief, so ultimately, the faith they should have should be in the assumptions they must make in order to continue living with confidence according to whatever expectations they've been led to have. Come to think of it, it's not that much different from the way religious people use it.