But it is a misjudgement, and one easily falsified, because not all atheists (why do you insist on capitalising that word anyway?) believe in objective morality. I know I certainly don't.
At the age of five, Skagra decided emphatically that God did not exist. This revelation tends to make most people in the universe who have it react in one of two ways - with relief or with despair. Only Skagra responded to it by thinking, 'Wait a second. That means there's a situation vacant.'