When you like chocolate ice-cream and your friend likes vanilla you probably don't say, "you ought to like chocolate". You realize it's a matter of subjective taste.
How about morality? Does subjective morality "work"?
It would if it were posited as a mere matter of preference. Some people enjoy killing other people. Most people don't. Most of us would not answer in response to the person who does, "you like killing people; personally, I am against it". We also probably wouldn't add, "But, I wouldn't want to impose my personal morality on you". Imposing our morality on the person is exactly what we would want to do.
Why? Do we do it because, a) we can (i.e., we have the power to do so), b) because there is a social consensus (majority rule -- which could change), or c) because murder is actually, really wrong and imposing this morality on the would-be murderer is the right thing to do? But, if it is the "right" thing to do, where does "right" (vs. "wrong") come from? What is its foundation?
When we say that killing the innocent is wrong, we are saying something closer to, or similar to, saying, "two plus two does not equal five". It's not just a matter of preference or taste or upbringing or personal or mere utilitarian values or evolutionary wiring -- killing the innocent is actually wrong (in a way that could never be true if we are the products of mere darwinian wiring). It's like moral law is just as real as mathematics or physics. In other words, we are postulating objective morality.
(Digression: this view, if accepted, provides a strong reason for why Jesus had to die on the cross -- the penalty for transgressions, like the mathematics of debt, had to be paid for the equilibrium of justice to be restored.)
There is (or at least appears to be) an "ought" to morality that people assume is actual and real beyond the mere imposition of personal or communal beliefs and values on others. We certainly assume there is.
I see this all the time on this blog. People think there is a right and a wrong way to be treated. If I mistreat them, they don't say, "I don't like it when you do this"; their comment is much closer to, "that was wrong of you -- you ought not to have done that".
I feel the same way. If someone deliberately short-changes me at the check-out, my reaction is not, "I don't like it when you do that", or, "this does not promote social harmony", my reaction is much deeper and visceral -- "I have been sinned against; what you did to me was WRONG".
This is a conundrum for the person who posits an uncreated universe devoid of meaning, purpose, and values, and man a mere unintended player who happened to "show up".
It is of course no problem for theists.
Do the math. Does it add up for you?
Regain your humanity. Rebel against the atheist machine.™