
The first avowed atheists in Europe rejected the authenticity of scripture together with the belief in afterlife rewards and punishments, and they generally rejected the idea of natural law in favour of a contractarian understanding of morality as a humanly devised social contract. It followed, so theists thought, that atheists would therefore do whatever they liked, an important suppressed premise here being that human beings are fundamentally fallen and not naturally inclined to behave well. If God were not to exist, morality (private and public) would have no foundation.
However, despite the accusations of religious apologists, the first avowed atheists in Europe were not interested in rejecting morality in general, but rather in naturalising and amending the traditional theistic morality.