One could argue that, sure. But your worldview doesn't allow you to argue it.One could argue, that on the basis of an atheistic worldview, this forfeits them human rights by default.
If an atheist, for example, believes he is identical to another animal, then why, for example, should killing an atheist merit a charge other than perhaps animal cruelty?
Regardless of biological relations and taxonomies, such as the zoological record and mankind's ancestral past as documented via the genetic records, in the context of civilization, mankind is held to be of a kind more deserving of rights than other animals.
On this, then, an atheist can't assert that he or she deserves human rights at all to begin with, other than appealing to some "faith" or some nonscientific faith-based set of principles, such as Secular Humanism, which just hold based on blind faith or axioms that Humans are special and more deserving of rights than other animals are.
This isn't saying that atheists don't deserve human rights, just that they can't rationalize it without appealing to "blind faith", or a set of faith-based principles or religious axioms like "Humanism".
According to your worldview atheists have inalienable rights for no other reason than they are God's creatures.