It's pretty simple, really. Those who adhere to man's morality want the world to be a better place with liberty, justice, human rights, equality, progress, quality of life for all of us. That is what we strive for. Those who think that they are adhering to god's righteousness want the world to be way more fucked up than it already is.
A mind is a terrible thing to waste -- don't pollute it with bullshit.