A culture which values women must be equal to one which subjugates them.
A culture which murders homosexuals must be equal to one which values them, like, say, the Greeks.
A culture which conquers and kills people who differ from them must be equal to the one which seeks only to live in peace.
Logically, all of this is implied when the claim is made that we cannot “judge” other cultures morally. Everything is equal to everything.
And, to be clear, seeking to understand others is always a useful practice. Finding the good and the bad is always useful. Seeking evolution is always good. It is not either good or bad, but that there should be a continuum seems to me a necessary conclusion if one is to act in a principled fashion, with principles being a necessary element in true cultural and social order.
But when, as one example, the British put an end to the practice of more or less forcing widowed women to burn themselves to death–living, with no sedative–on their husbands funeral pyres, this was a win for Goodness.
When the put an end to the cult of sacrificial murder which gives us the word “thug”, that was a win for Goodness.
Western Liberal values, in general, have made the world more peaceful, more prosperous, more just on nearly any scale, and, arguably, better, with the sole exception that we have not solved the problem of replacing indigenous religions with something truly better. We “gave” Christianity to much of the world, then abandoned it ourselves. This is our one truly great, gaping failure, and we need to fix it.
That, obviously, is the focus of my own efforts on a daily basis.