If someone will do something that has no meaning, or no purpose, then they 'in theory' will be able to do things without thinking or feeling about it.
If someone asks you to do something that you think has no reason, and you will do it, then you are more likely to do something that you think is wrong.
it is determining followship and if someone will follow without thought, if they are a non thinker, non feeler, that person can be used for any purpose.
It is a check to see if someone can become your tool, or if they will think and feel.
I think the thing that told Abraham to kill his child, and the thing that told him not to, were different things. One was the bad side trying to get him to continue blind followship in a way to create much grief and suffering, the other trying to explain to him that it was not needed nor the thing to do. Although I know most of the telling of that story is about blind followship.
Not sure if they ever mentioned the actual voice that told him not to hurt his children, but I think it was Michael. But that is just my guess.