I'm living on the planet on which Paul Tillich already got to the existential aspect of religious faith, and on which Emile Durkheim already explained the social, tribal aspects of religion and of the sacred/profane distinction, which apply to atheistic groups too.

The word worship derives from "worth," so if you hold something to be especially worthy, you tend to worship that thing in practice. There are degrees in all of this, as well as hypocrisy and phony shows of religiosity. None of that affects the connection between genuine estimations of ultimate worth, sacredness, and functional religiosity.

Of course, you can define these words as you like to make atheism antithetical to religion, such as by equating religion with theism. In that case, you'd be missing out on the existential and sociological aspects of religion that I build on.