Moral Relativism is the concept that there are NO universal standards of right and wrong, with many arguing against any universal standards often claiming, "There's only MY truth and YOUR truth." Yet funny, is it not, that such people nonetheless tend to assert THEIR version of truth, right and wrong is somehow superior to whatever yours is?
Here is an excellent quick primer which completely refutes assertions that moral relativism is credible:
https://www.youtube.com/watch?v=CpYFZmMxMqc