How to easily defeat any argument for God

[GrandizerII]

Somehow you say you accept objective morality, and yet you're forced to implicate a God that arbitrarily standardises morality.

Not to speak for Acrobat, here. But if he's following standard Christian theology, he would never say that God "arbitrarily standardizes morality." 

It's not arbitrary to say that health, for example, is good for human flourishing while sickness isn't. This is in the nature of what people are. 

The Christian view is that God is the final cause of this goodness. Health, for example, isn't good because God arbitrarily decreed it. Health is good because it is good for you, and God is the end point where all the goodness points.

It all depends on whether it is possible for the Holocaust to be morally right in accordance with the Good. If it is, then it's arbitrary. If it isn't, then it has nothing to do with the Good/God, but something about the Holocaust act itself.

The first part of your last sentence seems to indicate the latter, but then there is no need for it point to any God (or Platonic Good) as an end. It is sufficiently true on its own.

Now, I understand that getting from objective good to God as the final cause requires a number of additional arguments. But this is just to show that nothing is arbitrary about God's goodness.

I think it was best argued on this old thread by the poster called Ignorant. If you care to get the argument, scroll down for his posts and then follow the dialogue:

https://atheistforums.org/thread-31721-page-2.html

I'll have a look later, thanks.