I never believed in a God. [...] There may have been times when I wondered if there might be a God, but it always seemed to me wildly implausible tha… - Peter Singer

Since ancient times, philosophers have maintained that to strive too hard for one's own happiness is self-defeating.

If evolution is a struggle for survival, why hasn't it ruthlessly eliminated altruists, who seem to increase another's prospects of survival at the cost of their own?

The kind of equality utilitarianism supports is given by Bentham’s formula...: ‘everybody to count for one, and nobody for more than one’...Utilitarianism seeks to maximize happiness, and in deciding how to calculate whether happiness is being maximized, no one’s pleasures or pains should count for less because they are peasants rather than aristocrats, slaves rather than slave-owners, Africans rather than Europeans, poor rather than rich, illiterates rather than doctors of philosophy, children rather than adults, females rather than males, or even, as we have seen, non-human animals rather than human beings.