If God changed his mind

[robvalue]

Three people have now told me they would refuse to kill their family if god commanded it. (I'm very glad to hear that of course.) And I think they also claim morality comes only from god. So I don't understand on what grounds they can refuse. Are they finally admitting that in fact morality doesn't come from god?

The fact that they know this in advance means they are aware of some standard of actions being wrong, even if god says they are right. So how can morality just come from god? I'm not trying to be a clever arsehole, I'm serious. How can god "cross a line" if he makes the line?

I'd love an answer for this It seems an impossible conundrum. I won't ask people specifically to answer, but for anyone who would refuse to do what God said past a certain point, I'd like to know how you justify it.

If you wouldn't refuse to do absolutely anything God said, that is even more scary

To clarify, this is your God. You know for sure. It's not a fake God. If you "know" this would never happen, then you can safely answer a hypothetical that will never happen, right?