here. I lost sight of that when you suggested we could resolve the problem by placing "can not" with "will not", and I elaborated on why it's not quite that simple a solution, but, having identified that oversight, it's plainly in view again.
Also, I prefer to stick to my own example of "child rape" over "murder" to avoid the confusion between 'killing' and 'murder', and it provides less room for useless, unproductive, semantic quibbling. You can use whatever examples you want going forward, of course. But I intend to stick with mine when it serves my purposes, because I chose specifically it for the reasons I've described above.
Last, I'm completely fine with abandoning terms like "objective" and "intrinsic" going forward. I used them mostly for the sake of brevity, but it's obviously just making everything foggy.
Another thing I've failed to made explicit, and likely isn't obvious to you (being someone who doesn't appear, typically, to delve in the specifics of religions when engaging in theistic topics) is that Christians often rely on non-theistic, philosophical concepts (such as the Harm Principle, for example) when defending their version of morality. For example, they might refer to the harm same-sex marriage will do to society when describing why gay marriage is wrong. But the problem is that they can't rely on such principles because, as you rightly point out, if God can change the moral status of anything, what was a moral principle today could very well be an immoral principle tomorrow. And, when you look at some of the acts in the Bible where God has had direct influence, there seems to be a complete disregard for those principles on God's part, which strongly suggests that whatever practical reasons WE may have for behaving in some way, those reasons ultimately mean nothing.
Consider earlier when talking about acts at 1) harm the victim 2) do not help in any way and therefore is 3) are instances of unnecessary suffering. These are practical reasons that virtually any critically-thinking person will invoke when describing what makes something like rape, theft, or murder actually immoral. And, they are practical reasons that would be unreasonable to disregard. The problem with someone who holds to Divine Command Theory (or ANY theory that holds that there is an ultimate moral arbiter who can change the rules however they want, whenever they want), is that those practical reasons aren't actually available to them in argumentation because they hold that God - and ONLY God - has the ultimate say-so, no matter what.
Let's refer to someone to hold to Divine Command Theory as "DCT".
Suppose that DCT #1 holds that gay marriage is immoral - They hold that it is immoral because God said so (The Old Testament forbids homosexuality)
Suppose that DCT #2 holds that gay marriage is moral - They hold that it is moral because God said so (Jesus said "Judge not, lest ye be judged yourself" and was known to dine with adulterers and the like)
On what basis can they resolve their differences? Can they rely on any practical reasons (that their opponent would be irrational to disregard) in making their case? Nope. The only principle they can rely on is the supposedly "objective" idea that God agrees with them. And if DCT #1 disagrees with DCT #2 (or anyone, for that matter), then there's an intellectual stalemate.
So the problem with DCT theory is that, if you are an advocate, it severely stifles critical thinking in the realm of moral philosophy, while at the same time being touted as the ultimate standard for morality.