The Rational Paradigm of Non-Religious Morals
For christians who want to gain access to heaven in the afterlife, rational morals include the precept to give and to sacrifice more than to receive and to expect and to suffer more than to harm others.
For non-religious people the rational approach to morals is different. Without a rewarding and punishing god in the afterlife, it suffices to have a fair and just balance of giving and receiving. This can work as long as nobody takes more than what he gets.
I consider Epicurus’ principle of not harming and not being harmed as the most appropriate. Good and bad deeds do not have the same impact. An atrocious bad deed has often irreversible life long consequences for the victim. But I cannot think of any good deed with truly irreversible effects. Someone can save a person from drowning. But there is no guaranty that the saved person does no die in a car accident the next day. Therefore it is more important to avoid bad deeds.
Suitable for non-religious morals is the tit-for-tat strategy. When everybody starts with cooperation and reciprocates cooperation, the system can work.
For me personally such morals suffice to consider myself as a decent person and to feel good about myself. I have the impression that some non-religious people overreact to christian accusations of being immoral by competing to be more moral than the christians.