To conform to a recognized code or system of rules of what is right or wrong and to behave accordingly. How do we know what is right or wrong? We use our empathy and reason, and we reflect on how our decisions effect the people around us. Plain empathy can trigger natural help responses to others' distress and create natural aversion to causing others harm. Two prerequisites for reliable moral assessment are reason and accurate, relevant information. Sound reasoning won't lead to valid assessments if we're operating with flawed information, nor will sound information if our reasoning is flawed. If a person is not a sociopath and is genuinely moral, such that the happiness and suffering of others really matters to them, then neither the presence nor absence of any gods will fundamentally change anything for them in terms of moral decisions. An other point is that morality is required for human social structures and human communities to survive at all. Neither the presence nor the absence of any gods can change this, and while religious theists may find that their beliefs impact their moral decisions, they cannot claim that their beliefs are prerequisites for making any moral decisions at all. We can all be good without gods, have a nice day.
Our empathy centers work so heavily that we feel not only the pain of other humans, but other creatures and even sense inanimate objects as having feelings. Now that's an overboard empathy system.
These evolved from over a few million years of social cohesion and need for the support of other humans, along with our extremely long gestation period and reliance on our parents/guardians.
We are extremely moralistic, naturally, without the need for dictated Traditional morality nor any instructions from an imaginary supreme being like a God.