[Here I have written incompletely about a subject at first, and at second, I grope toward a better articulation.]
Atheists cannot truly 'speak'. True speech is a vow, in which one puts his life behind his words. All vows are made in the name (because of the nature of) of God.
I have erred. There is more to it. Anyone who speaks, must base this speech on having been spoken to before, if only as his or her parents spoke to the person now speaking when the person was a child.
Thus, anyone who speaks acknowledges, though inarticulatedly, the Speaker, Who spoke the creation into existence.
In this perspective, there are no atheist speakers.
I must contemplate more about this.
Love in King Jesus,
confesio, contritio, satisficio
PS: I think it is the difference between self-consciousness and articulation, in the case of vows, and the lack thereof in what I have written immediately above.