One of the disadvantages (perhaps the main one) of not accepting the existence of a higher power that takes a direct interest in human affairs is the limitation placed on expletives. What can you say instead of "Oh my God!" or "Thank God!" or "Go to Hell!" or "Damn it all!" or "What the Hell!" or "not worth a damn" or all the other handy expressions? Euphemisms such as "Good gosh" are also ruled out, as they are just indirect references to the same core belief.
There are of course the usual crude sexual and scatological expressions, but they rarely serve exactly the same purpose.
As a result, my speech is somewhat restrained. But I suppose if one claims to be an unbeliever on rational grounds, that rationalism should extend to the rest of life, and limit the need for expletives. I find it to be so, but sometimes one just needs to let loose with an emotional response.