Yes, and if you actually understood English you'd realise that that particular definition is effectively a colloquialism i.e. not a literal usage.
And you're also ignoring the fact that atheism also covers non-belief: how can one "devotedly follow" a non-belief? Or believe in a non-belief?
It's a definition regardless what you think, and it
fits with my analasys.
Atheism means non-belief in God.
jan.