Atheists can take issue with that all they want but, that is based on their own individual beliefs. Speaking by definition only, atheism is lack of belief in a deity. I have seen many atheists on the forum assert that atheism is nothing more than that (usually because they are offended that people considered atheism to be a belief system
)
Anyway, I find no problem in the assertion that atheism alone does not imply lack of spirituality. I dont know if you are from the USA but, here, basically an atheist is associated with irreligious and scientific materialist, to put it very generally. While these things are associated with the term
atheism because of the prevalence of these things occurring at the same time, many people take atheism, in and of itself, to imply a lack of spirituality as well. I find it illogical to imply that atheism is inherently lacking in spirituality. It changes from one person to the next, just like how a person could be a catholic and not really practice their religion. Just because a (maybe) majority of atheists are lacking in spirituality and are materialists who only follow science, does not mean that
atheism implies lack of spirituality.
Like I mentioned earlier, I guess the term just has all this baggage associated with it at this point. Perhaps terms like non-theist or trans-theist are more appropriate for a spirituality without a god concept.