The Tinkerbell Effect.

[Esquilax]

You can be as relativist as you like, but you're still bound to a physical universe that has truths one can state about it, and therefore has actions that are objectionable.

I'm interested to hear what these objective morals are in this context. Could you elaborate further?

Sure. It's just a matter of extrapolating out from what we know to be true about the universe; we're living beings who- generally speaking- like being alive, and we only know of the one life we have for one hundred percent certainty. Therefore, life is preferable to death (generally) in that only the living can improve their circumstances. So indiscriminate murder is wrong because it robs the victims of this ability, leaving aside the issue of suffering.

In fact, causing suffering can be seen as an objectively immoral practice in general, because we don't like suffering, and those actions that cause suffering without reason (rape, assault, stuff like that) can be seen as immoral actions by that standard.

Conversely, charitable actions that provide benefit to others are objectively good in that they provide only benefit; if I go volunteer for a charity there's a cost to me personally in the form of time spent, but a benefit to the broader community, and that's good. Generally, we do prize good in a general or community sense over personal good, which is why charity is good despite the personal cost, but rape and theft (very good for the individual, unhealthy for the larger group) are immoral.

Anyway, there are numerous caveats, and actually explaining the whole thing would take forever, but the basics are life over death, pleasure over pain... very simple objective moral truths, but enough for a foundation.