It depends on the atheist. And I may jumble my atheistic terms around, as I am not one, but there are "weak" and "strong" atheists. For those weak, if I remember correctly, they do not believe in gods but are not denying their existence (not the same as agnosticism). Strong, as its counterpart, actively denies the existence of gods. It can be said of the latter that they truly believe no gods exist. The issue that comes up with many atheists is they want to posit themselves as both, like Sgt. Lynch. He wants to say that he merely has a "lack of believe" yet also actively denies the existence of such a being (or beings). You cannot posit both.
Believe it or not, silent songs do exist. Don't ask me why, I cannot tell you. I only know of this because my friend is a musician. 🙂↕️ Bald can also be a hairstyle, assuming the person actively still grows hair and chooses to shave it (although one can argue that not having hair is a forced hairstyle).
Justification for believing or not believing in something is subjective. What qualifies as sufficient evidence is subjective.