system
Given the following post, respond as if you're commenting on Reddit:
human
CMV: There is no such thing as objective morality

Morality is completely subjective depending on the person, culture, upbringing, time period... There is no such thing as objective morality.

Islamic terrorists for example view killing apostates and non followers as completely moral. 
Long ago, slavery wasn’t viewed as immoral because in the eyes of the owners, the soaves were less than human and so everything was perfectly justified.
In the twisted minds of the Nazis, their actions were not immoral.
Homosexuality was viewed as immoral even in the west a few decades ago.

These are just a few examples of how morality varies depending on a lot of factors. Still, numerous people believe that morality is something objective.

So basically to change my view, you should simply show me that there can be some forms of objective morality.
gpt
All these people believed their actions were decreasing the amount of suffering in the world. Religious terrorists believe their opponents are going to hell anyway — better to kill them before they can convert more to Satan’s cause, damning their souls. Slave owners argued slaves were happier enslaved. Nazis thought they were creating a utopian society, and thought Jews were the root cause of suffering in the world.

All three groups were either objectively wrong about the facts (salves were not more happy, Jews were not the root cause of suffering, the best way to make Islam thrive is through acts of terrorism) or making claims that are unfalsifiable (heathens will be punished in the afterlife).

At the time of all these movements, there were counter movements arguing that these people were objectively wrong. That slaves are better off enslaved is not a matter of subjective opinion, it’s a matter than can be disproven using empirical evidence and logic. Same with Nazism, same with theological morality.

Whereas the root claim — people would be better off without suffering — is pretty objective, as humans are designed to avoid suffering. Morality is rational group strategy to avoid group suffering. One can approach that project just as objectively as doctors approach a triage situation — and how to best act in a triage situation is a branch of bio-ethics.

I’d also argue that objective morality is morality that approaches things objectively — with logical arguments and empirical evidence. We approach medicine rationally — how do we medically cure suffering? That’s not a subjective matter. Morality has the same goal — how do we socially, culturally and personally prevent suffering? There are real answers to these questions.