Two is right, one isn't. Government law doesn't equate to a proclamation of objective morality. I'm not atheist.
That's not the contradiction.
The contradiction is this:
(As you agree with my second bullet) Atheists assert subjective morality and then go on to condemn other acts as moral or immoral.
For Example:
Person: "Rape is right to me, man."
Atheist: "No. You are absolutely wrong. Rape is wrong."
Person: "Pushing my views down someone else's throat is right to me."
Atheist: "No. You are absolutely wrong. You can believe anything you want just don't push your views upon me, because pushing your views upon me would be objectively immoral."
So, you see, in moral subjectivism, no action can be objectively condemned as moral or immoral. You might with the might-makes-right argument and respond: "But wait, man, morals are selected by the majority of a society." Apply that to Nazi Germany, Apartheid South Africa, etc. Just because a majority of people assert a moral value doesn't mean that that value is objectively right or wrong.