It is telling that an atheist would even bother to seek a justification or excuse for his own disbelief.
My Spiritual discernment on such conduct is that they are more likely spiritually rebellious or doubtful than actually disbelieving. A "true" atheist, IMHO, is a metaphysical naturalist who doesn't believe but doesn't mind if you do - he seeks no justification and makes no excuses.
Do you have any evidence that more than a tiny fraction of people who don't believe in a deity are 'metaphysical naturalists'. Most atheist I know are empirical naturalists; they see no useful reason to posit and no hard evidence for a Deity. Their naturalism does not have metaphysical underpinnings; rather, they've noticed naturalism is a useful way to view the world, and see no pressing reason to abandon it.