“In 2023, approximately 72.5% of Americans identified as religious, with 27.5% being religiously unaffiliated.”
Religiosity is in decline, see the link, but no atheists are not in the majority. NB Important to note here that religiously unaffiliated need not mean atheistic, for a variety of reasons. In many parts of the US it also might be expedient to keep your atheism to yourself, certainly if you wanted to run for any sort of public office, for example. So the figures are a “best guess” if you like.
I am not sure what the OP means by “clarify” atheism, it is the lack or absence of belief in any deity or deities", and that seems pretty clear and concise to me. Nor do I see the need to promote it, as much as the need personally I have to challenge any pernicious beliefs religions try to peddle, including the core idea that we should owe more loyalty to a deity imagined to exist, than to other human beings who exist and can be harmed as an objective fact.
In a word humanism, I find this a more moral worldview, as its primary
priority is how we treat each other, over all other considerations, though this is not of course atheism, but nor are they mutually exclusive.