Depends on the 'god' concept. Some of them are logically incoherent. Logically incoherent beings cannot - and by extension, do not - exist.
For example, you might claim 'everyone knows my god exists', like certain brands of presuppositional apologists do, as per
Romans 1. But since I am aware of at least one person who does not know it - namely, me - I can be 100% certain your god does
not exist, because you've predicated his nature on a condition that I, and
only I, have direct access to.
So while the point holds in the broad sense, there are specific conditions in which I can truthfully claim 'there is no god (at least as far as you've described him)'.