What is Morality?

OK... here's something that has been bugging me for awhile, and some comments from an atheist have just prompted me to write this down. Question: What is morality? Merriam-Webster online defines it thus:

a : a doctrine or system of moral conduct
b: plural : particular moral principles or rules of conduct
3 : conformity to ideals of right human conduct
4 : moral conduct : virtue.

I don't know about you, but I hate definitions that rely on usage of the root of the word in question. So, here is the definition of moral:

a : of or relating to principles of right and wrong in behavior : ethical
b : expressing or teaching a conception of right behavior
c : conforming to a standard of right behavior
d : sanctioned by or operative on one's conscience or ethical judgment
e : capable of right and wrong action.

Great. How do we define 'right' actions versus 'wrong' actions? Again, I go to Merriam-Webster for some clarification on what is 'right':

1 : RIGHTEOUS, UPRIGHT
2 : being in accordance with what is just, good, or proper
3 : conforming to facts or truth : CORRECT
4 : SUITABLE, APPROPRIATE
5 : STRAIGHT
6 : GENUINE, REAL

I note that the first word mentioned by way of defining 'right' is again a form of the word in question! So here we go with 'righteous':

Righteous: 1. acting in accord with divine or moral law : free from guilt or sin
2 a : morally right or justifiable b : arising from an outraged sense of justice or morality

So let me see how this might all work: morality is moral conduct, and what is moral can be determined according to an ethical or right standard, a righteous principle.

So in essence, acting in accordance with what is just, good or proper, also known as being righteous, or practicing right behavior, is to act in accordance with divine or moral law, according to Merriam-Webster.

That last phrase interests me. Which is it? Is our society's definition of morality based on divine law, or upon moral law? And can there be a moral law apart from a divine statute? Because if morality traces its existence back to divine law, how can the very same legislators, judges and other politicians who insist, loudly and at times passionately, on a separation of church and state, turn right around and insist heisting money and property from one group of people to give to another group of people is justifiable on moral grounds? I mean, aren't they sort of crucifying their own sacred cow?

(And if it helps, divine is defined as: a : of, relating to, or proceeding directly from God or a god b : being a deity)